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Coatings
Painting Clinic articles from Products Finishing are selected and categorized by application for quick reference:Dye Sublimation Coating 05/01/09
I am looking for the names of suppliers of polymer coatings that can be used on ceramic tiles for dye sublimation treatment.
Painting Galvanized Steel 05/01/09
We have been painting solar collector assemblies, not the collectors themselves, but the structures that support them. These structures are fabricated from galvanized and plain steel parts, depending on their location in the assembly. Under certain conditions, the paint must withstand temperatures up to 300°F for extended periods of time. We have been applying a low-gloss black enamel to these structures. In this application the paint must last for several years in service without peeling, flaking or other deterioration. We have been getting customer complaints about paint peeling and flaking off the assemblies. What is the best way to solve our problem?
Vacuum Coating 05/01/09
I am interested in coating PVC foam boards with paint. I heard that vacuum coating is a process that will work for this application. Can you direct me to a company that can either supply the equipment to vacuum coat, or provide the service to vacuum coat? Are you aware of any other methods that could be used to coat these boards?
Wrinkle Finish 01/01/09
I am painting a machine tool sheet metal cover and having a hard time finding someone who can apply a wrinkle finish. All of the machines I work on are in the neighborhood of a half million dollars, so the need to match them is big! Help!
Painting Galvanized Tank 12/01/08
I have a 750–1000 gal galvanized holding tank used for maple syrup production. The tank has not been used for a number of years and has some surface rust. I would like to remove the rust and coat the inside of the tank to be able to use it again to store clear water, which will be used in our Reverse Osmosis machine. Because of the use and need for it to be food safe I am unsure of what to use to coat/paint it. Any ideas?
Temperature Control Coating 12/01/08
We are developing a small, thermally sensitive electronic enclosure unit which is carried on a boat. The temperature developed inside the unit is around 70°C. It is exposed to sun and also the marine atmospheric conditions all the time. Since it’s a water-tight unit, no vents are can be provided and no external refrigeration unit can be used. Can you suggest any coatings or paints that will protect the unit from solar radiation heating and keep the temperatures low within the unit?
Zinc-Rich Primer 12/01/08
I am the chief chemist at a paint plant. One of our customers wants a finish system using a zinc-rich primer. He also wants to use his existing TGIC-free topcoat. This question is in regards to issues we face with a zinc-rich primer and TGIC-free top coat. The coating thickness is 80 to 100 µm. After applying both the coats the painted test panels are failing mechanical properties like the mandrel bend test. It is also failing the falling ball impact test at 40 kg-cm. We are trying to resolve this issue. I would appreciate it if you could help with some solutions.
Painting Polypropylene 11/01/08
We are working to achieve a variegated appearance on mineral-filled polypropylene exterior siding, the substrate being injected molded. Our objective is to use a single-part, water-based coating. Our issue is adhesion of the coating on the multifaceted surfaces. We are working with flame pretreatment but are seeing inconsistencies. Adding to our confusion is the apparent lack of consistency from dyne solutions—we see wetting out of the dyne solutions from 35–70, but then the coating, which is a 38 dyne, doesn’t stick consistently.
Coating Polished Brass 10/01/08
We manufacture a line of decorative tubular railings and fittings. I was wondering if anybody had any ideas of what clear coating to put on polished brass, because we used a clear polyester topcoat on them and after three years, one of our customers complained about it developing what look like corrosion spots (I think caused by moisture) underneath the top coat.
Formulating Wire Enamels 10/01/08
I am a research engineer working on a project to develop a paint enamel to coat thin-gauge wires. I would like to know how to begin formulating. I already know the constituents of paint, but I do not know how much of each constituent to add and in what order? Please send me literature, handbooks, suggestions or Web sites that may be helpful in getting me started in formulating my enamel.
Paint Blistering 10/01/08
I am in charge of the paint line at a plant where we manufacture a line of timers housed in steel cases. In the past, these housings had been spray painted using conventional equipment. We have recently installed airless spray equipment to take advantage of paint savings due to decreased overspray and to comply with air quality standards. Now we are getting blisters in the paint. Is this due to the airless spray equipment? What can we do to remedy the problem?
Painting Porous Castings 09/01/08
I read the question from H.S. concerning the painting of porous magnesium castings with a baked epoxy. How about using a two-part epoxy or polyurethane and supplying low heat or no heat at all?
Transfer Efficiency 09/01/08
I would like to know more about TE. Can you give me any valuable information regarding improvement of TE in a painting process?
PAINTING POLYSTYRENE FOAM 08/01/08
I am the manager of a manufacturing facility that is old but in good condition. We are in the process of painting and freshening up the facility for an open house, and are wondering what sort of paint is required to refinish the insulating panels on the roof of our building. These panels, which are actually the plant ceiling, are made of thick polystyrene foam and are a blue color. The building is old and we presume the roof panels are, too. They are in good condition but unsightly and we’ve concluded that if we can paint the polystyrene foam it will really brighten up the plant. We are also aware that by painting them we may risk destroying them due to the nature of the material. What can you suggest as a solution to our problem?
More on Iron Phosphate over Zinc 07/01/08
I have a comment regarding a question in the May issue about delaminating on zinc substrates. Iron phosphates are very capable of providing good “morphology” and surface conditioning on zinc (nonferrous) alloy if fluoride is added to the bath. This is a standard and customary protocol requiring typically less than 0.1% F. Also, zirconium nanotechnology is capable of producing coatings on zinc without fluoride. The environmental considerations of zinc make using it extremely difficult for most customers.
Painting Magnesium Castings 07/01/08
For the past several months, we have been trying to supply a new customer with a die-cast magnesium product that is coated with a baked epoxy enamel. We have had no success and would like to know what we are doing wrong. The parts are cast, trimmed, pickled and then sent to the paint shop for coating. The results are a very high scrap rate because of blisters in the painted surface. We tried a number of other treatments such as pickling and sanding after pickling without success. Microscopic examination of the die-cast surface shows that it has a very porous surface. We tried without success to modify the casting process by increasing die temperature and changing shot speeds and dwell time using pure magnesium. I find this to be a very difficult problem. I would welcome any changes you can suggest.
Masking Threaded Holes 06/01/08
We are trying to paint a part that has a tapered port welded on it, basically a pipe thread. The customer is complaining about the paint interfering with the assembly operation. Since I am the director of quality control at my company, the complaint landed on my desk. If we plug the hole, the parts rust before they arrive at our customer’s shop. If we make the threaded plug diameter larger to accommodate the paint thickness, will it cause fitment issues?
Prep for Painting Over Powder 06/01/08
Our company is going through a corporate trade dress initiative that involves changing our exterior building colors. Currently, we have a number of locations that have powder coated window mullions that need to be changed in color. Is sanding the only method to get paint to adhere to powder coat, or can a good quality primer be used in lieu of sanding (provided there is no slip agent in the powder)? Obviously, what we want to avoid is paint blistering and peeling, which becomes an unsightly and continual maintenance issue. Are there specific types of primer and paint that you would recommend for this type of application?
Smoothing Rough Castings 06/01/08
We supply machined and rough castings to a number of industries. We have been applying a shop primer to prevent rusting. When a customer wants a smooth casting, we have been applying a fast-drying, lacquer-based body putty bought at an auto parts store to fill the pores before applying the shop primer. We recently have seen such an increase in orders that we decided to decrease production time by applying a baking primer to the castings. Now we are getting blisters on the painted castings. This may sound like a dumb question, but what can we do to solve this problem?
CAN’T RECOAT 05/01/08
As you know, stripping and recoating is very costly in terms of time and labor. We are now applying a new baking enamel coating that is very durable. We tried touch-up and recoating by spot repair and total recoating with a durable air-dry paint, but we can’t get the touch-up paint to adhere to the damaged parts. I’ve never seen anything like it.
Is recoating products a common problem? What can we do about it?
FLAT CLEAR FINISHES 05/01/08
Are different agents more efficient in their ability to create a flat finish? What would be your formula for the perfect clear coat?
Coating Steel Fasteners 04/01/08
I am a manufacturing engineer responsible for product development for a supplier of fasteners and fastener tools. We are currently exploring different coatings for screws and nails used in pressure-treated lumber-based building projects such as decks and other outdoor structures. We’re interested in different coating technologies with regard to corrosion resistance, and are getting ready to make a pretty big investment in a coating technology. We’re using this time to explore the various technologies on the market. Our fasteners are made of steel, and they’re being used on and in treated lumber. There is sometimes interaction with other metal connectors. The big issue right now is finding a coating that can hold up to 1,000 hr of salt spray. ACQ (alkaline copper quaternary), used to preserve the lumber, plays a big role, too, because it accelerates corrosion. And cosmetics/aesthetics are important as well. We’ve had the greatest amount of success with zinc nickel plating (400 hr in salt spray). At this point, we are interested in any coating technology, including plating technologies, organic technologies, or even a plating/organic hybrid technology.
Finishing System Durability 04/01/08
While the specific paint chemistry can clearly have dramatic impact on the durability of the finished component, the use of effective surface cleaning and conversion coating practices may actually have an even greater impact. If end users and coatings applicators are looking to improve paint adhesion and corrosion resistance, it is critical to consider the surface preparation of the component.
Primer Getting Thick 04/01/08
My paint line foreman tells me that the two-component primer we are using is getting thicker by the minute. Because the pot life was long enough, we had been mixing up a five-gallon batch of primer every day and applying it using siphon-feed spray guns on our products. We did this for many years without any problems. The thickening problem started after we started using a five-gallon pressure pot to feed our spray guns. Now the primer gets so thick that it clogs the spray guns. Adding solvent doesn’t help. When we go back to siphon-feed spray guns, the problem goes away and we can mix up a five-gallon batch that lasts for two shifts. We went to the five-gallon pressure pot to eliminate refilling the small siphon cups. Our production has increased to where it is more convenient to use the five-gallon pressure pots. What can we do?
Conferences, Shows and Schools 03/01/08
I'm getting more and more calls to do powder coating and ceramic coating, but I don't have a clue where to start. Could you recommend a good workshop for beginners here on the East Coast where I could learn more about these type coatings and how to apply them? Would the Electrocoat Conference be over my head?
Paint Adhesion to Plated Plastic 03/01/08
I am the senior engineering manager in charge of product development execution. I received your name from a NASF member in Dayton, OH. We're a contract manufacturer and I'm troubleshooting a paint adhesion issue on a custom part. I'm not sure if you can help me, but if you know how I can locate a consultant or other resource to help resolve a production issue, I would greatly appreciate the assistance. The problem comes about after a translucent paint is applied over a chrome-plated polycarbonate/ABS plastic substrate. I'm assuming that the chrome plating must be prepared (cleaned or etched) before paint application, but I need some recommendations to forward to the factory.
Painting and Finishing 02/01/08
I am in the business of reconditioning, repairing and customizing guitars. I am painting some of them and I require some advice on finishing the job.
Evaluating Mid-Gloss Black 01/01/08
We measure our mid-gloss black color using a color difference meter. We are having a hard time correlating the instrumental color values to the visual perception of the finished black paint. In many cases, we found that when a sample has good instrumental color match to the standard, it does not look good visually, and vice-versa. What is the best way to evaluate the black color, which has 60° gloss of 55–65 units?
Class A Finish 12/01/07
We make composite parts with glass fiber reinforcement in a vinyl ester matrix. A customer has asked us to make parts requiring a Class A surface finish. Can you help me to understand what that is?
Epoxy Paints 12/01/07
What is the difference between an epoxy and epoxy-polyamide cured system? Someone said, "it's the curing agent." Which one is better.?
Painting Type 304 Stainless Steel 12/01/07
I would like to know if it is possible to paint Type 304 stainless steel with a high-solids epoxy-type paint (per MIL-C-22750). If not, can you recommend a paint system that would be more suitable for this alloy? What type of primer is recommended for this surface?
Powder Coatings vs. Liquids 12/01/07
We are considering adding a small parts coating line due to cost and volume, and would like to consider a powder epoxy system. How do the powder epoxies compare to high-end wet epoxies? Also, how do the zinc phosphate treatments for powder coating compare to a zinc primer? Although we doubt we can beat the zinc/epoxy system we currently have, is it possible properly pretreated steel with a powder epoxy may outperform a zinc/urethane system? Is washing as good as blasting?
Alternatives to Phosphate 11/01/07
I'm the manager of application engineering for a company that makes valves. The valves are phosphated and then painted. We also use phosphate coating to provide corrosion resistance to a number of carbon steel components before painting. Vapors from the hot tanks are a problem for factory employees working near this coating system.We're looking for a more environmentally friendly coating system with at least similar corrosion resistance qualities. I would appreciate your recommendation for an alternative to the phosphate coating process.
Coloring Galvanized Wire 11/01/07
I am currently working on a project for a client who wishes to in-line color galvanized steel wires. The idea is to design a system that paint the wires. At this stage, we are looking for suitable paints and painting techniques that would serve the purpose. The main constraints for coloring the wires are quick curing (about 3 sec) and coating thickness <10 µm. Can you suggest any possible technique that will paint the wires?
Painting Structural Steel Indoors 11/01/07
I'm the facilities manager of a plating shop that's faced with repainting the structural steel components of a 12-year-old building. We plan to sand blast for surface prep. First, what media is recommended for blasting structural steel indoors? Is free silica in sand an issue only when blasting, or as a residual factor as well? What paint system is recommended for plating shop applications expecting a 20- to 30-year service life? Site ventilation is good and humidity is usually under control, but there are exceptional days. If more than one type of coating could perform, then what are the economics of the different systems?
Centrifugal Coating 10/01/07
I am the manager of finishing operations. My plant produces a number of small parts, such as mounting clips and angles, that need to be cleaned and painted. They range in size from 1 x 1 x 1 inch to 1 ½ x 3 x 8 inches. Most of these parts have flat surfaces. Since the parts must have high corrosion resistance, they are zinc phosphated before painting. However, coating appearance is not critical. We spend a lot of time racking parts by hand, after which they are pretreated on a six stage zinc phosphate line and painted by spraying. We have heard the terms "centrifuging" and "tumbling" finishing and wonder if these are possible processes for us to use on our products. What is your opinion?
Paint Technology Information 09/25/07
I'm a graduate student pursuing my master's degree in integrated technology in polymer science and technology. Right now, I've undertaken a project in polymer painting. I recently came across your Web site and found it quite helpful. Can you please help me further by providing information sources on the details about the new inventions in this field, for example the paints mostly used for industrial purposes especially the automobile industry, also the processes involved in painting and the obstacles encountered and particularly the defects that might occur during painting.
Wet Adhesion Test Problem 09/25/07
We have problems with the wet adhesion test of epoxy primer 515K011 over colorless chemical conversion coating. We test wet adhesion according to FED STD 141 method 6301. The test pieces for checking adhesion are 2024 T3 aluminum alloy, clad or unclad. We have some questions about the wet adhesion test:
- Is it necessary to cure paint coatings seven or 14 days before the wet adhesion test?
- Is it necessary to protect the edges of test panels before the water immersion test? S. G.
Check Steel Type 09/01/07
I read with interest your reply to E. O. concerning his adhesion problem to the steel he's purchasing from a new supplier. Although I completely agree with your answer regarding cleaning of the surface, you only touch on the type of steel that he uses. Cold-rolled sheet steel goes through a few processes, and this carbon steel can also be alloyed in varying amounts, depending upon end use. I would have advised him to contact his sheet metal supplier first since the only change was the steel source.
"Novel" Radiation Curing 08/01/07
I just read some literature regarding UV radiation curing of organic coatings and the benefits it brings to the coatings industry. I would like to know whether this technology can be extended to paints for exterior applications with moderate or high solids and PVCs. More importantly, where can I get a list of companies who supply this novel technology?
Black Finish for Aluminum 07/01/07
I'm a manufacturing engineer in charge of the finishing department at my plant. We produce machinery control instruments for the oil drilling industry. I'm currently having problems with the front panel of an instrument case used on offshore drilling rigs. The case is fabricated from 6061 aluminum plate and has an instrument display bezel that's also machined from 6061 aluminum plate. It's engraved with a logo, lettered and painted black Because of exposure to the atmosphere and the fact that it's mounted on an offshore drilling rig where it's exposed to unusually rough treatment, the paint gets scratched or damaged and fades. I have tried black anodizing and I found that it also fades when exposed to sunlight and sea mist. I'm hoping you can offer suggestions for a black finish that's both tough and durable.
Coating Interior Surface 07/01/07
In your March 2006 Painting Clinic, "Coating Interior Surfaces", you discuss how to coat the inside of a 1 inch diameter tube, and ask if readers have any additional suggestions. We use a miniature foam roller on a metal rod to coat the inside of a 3/4 inch ID tube.
Pigment to Binder Ratio Calculation 07/01/07
I am a paint chemist. I work in a lab at a coatings company and am currently working on the pigment to binder (p/b) ratio of one our paints. But when I come to the formula to make my calculation, I'm having a little bit of trouble. For my percent ash value the formula reads: % ash value = ((100% -% moisture of sample)/%NV) × 100. The problem I encounter is that I'm unable to figure out the percent moisture of sample. Is there a formula I'm missing?
Pretreatment of Aluminum 07/01/07
I'm the president of a company that finishes aluminum products. We need your advice on problems we experience from time to time in painting our products. Some time ago in one of your answers, you pointed out that you recommended anodizing first and then chromate conversion coating as a pretreatment for adhesives and painting of aluminum.
Spray Can Applicable Thermochromic paint 07/01/07
What thermochromic products would you recommend that offer the greatest color change, and what would those colors be? What is the temperature change necessary to effect this color change? How long would the change be visible with unassisted air cooling back to room temperature? Are these materials safe enough for a consumer to apply outdoors without concern for exposure or inhalation hazards?
Stripping Coatings 07/01/07
own a custom painting shop that serves plants that outsource their finishing operations. We also do refinishing, which involves stripping of existing coatings. Because of our layout, we use chemical strippers. I have a good background on the chemistry of solvent-containing and waterborne materials, but I will have to do some additional work on better chemical strippers for powder coatings because we find them more difficult to strip. My guess is that in addition to being thicker, possibly denser and less porous, there are some chemical differences as well. Can you steer me toward some sources of this type of information?
Cement Truck Finish 06/01/07
We manufacture cement trucks. These are both the rotating drum type for general use and the open-top tub type used at highway construction sites. The mixers and tubs are made from 14-gage hot rolled steel. The paint must be resistant to abrasion by the aggregate in the mix, and to corrosion from the alkali in the cement and the acid in the wash water used for cleanup. We do our painting out in the manufacturing shop floor, although we plan to add a paint line to our shop. However, we are having paint problems. These problems run from primer and paint peeling to severe rusting. Before we order any painting and metal preparation equipment, we need to know the materials to use and procedures to follow to improve our paint finish.
Painting Aluminum Castings 06/01/07
My company manufactures and paints small cast aluminum parts for interior decorative use. These parts are never touched or handled in service. However, they may be subject to cold weather temperatures in storage prior to their interior installation. To decorate these parts, we perform the following steps prior to the final decorative spray paint coat: aluminum cleaner bath, aluminum etchant, conversion coating and finally a primer coat. How many of these customary aluminum preparatory steps can we eliminate from our process? We've experimented with eliminating the conversion coating and primer coat without any adverse affects over the short run.
Paint Blistering On Plastic Bumpers 05/01/07
We are a painting subcontractor for automotive plastic parts-bumpers, door handles, side mirrors, and so on-here in the Philippines. After about three months, blisters appear on the surface of the part. The size of blisters vary from 1–4mm in diameter. The problem appears on a portion of the parts only, not on the whole surface. Blisters appear both scattered and grouped together. The problem is on the rear bumper only. The front bumper has no problem at all. Prior to painting, we noticed that the primer on the rear bumper is thinner than the front. Could you please help us find the cause of the problem?
Painting Aluminum and Brass Castings 05/01/07
We produce brass and aluminum castings used as nozzles. valves, hose and hydrant connections, etc. These products are used by the fire protection industry for indoor applications. Because of possible rough handling, the coating for these products must be durable.
Occasionally, we have small orders for parts that must be painted red. The parts are rough castings of brass and aluminum, and the paint is applied with a brush. However, our problem is that we cannot find a paint that will adhere to the castings.
It should have a fair to medium luster. Most importantly, it must adhere to brass and aluminum.
Clear Base Coat For Dye Sublimation 04/01/07
I am looking for a supplier of a clear coating to be applied over a metal plate substrates (aluminum, stainless steel, etc.) to which I will then apply an image using dye sublimation. Do you know of a supplier of coated plates or medallions?
Painting Over Powder Coatings 04/01/07
We make pole mounted distribution transformers for outdoor environments. We powder coat our transformer tanks with pure polyester powder. One of our customers is demanding we paint identification patches on transformer in different colors.
Speeding Up Acrylic Enamel Curing 04/01/07
I was penny-wise and pound foolish and sprayed acrylic enamel a few days ago without hardener. I didn't think I really needed the hardener since the acrylic dries in a few hours but I didn't realize it doesn't get hard until it cures, which can take a long time.
Transfer Efficiency And Paint Spray Distribution 04/01/07
Our facility has a paint application process using high solids solvent based paints. The system is an electrostatic disc application process. I'm trying to estimate particulate distribution for three areas: the metal parts, overspray to the surrounding plastic covered walls/floor and to the filter bank on the exhaust stack.
UV Radiation Causing Tarnishing? 04/01/07
In the January, 2007, Painting Clinic, I read the question from C. S., "Clearcoats For Brass", regarding the tarnishing of the brass parts he manufactures. Somewhere in my memory, I have the thought of UV playing a part in tarnishing during exterior exposure. I remember having to add UV inhibitors to some formulations. I do remember that UV will break down epoxy coatings.
Drying Time Chart 03/01/07
I have been tasked to determine manufacturing costs for painting operations. I have a handle on painting costs for products going through the baking oven. We apply air drying paints to products that are too large to put through our baking oven.
One-Stage Iron Phosphate 03/01/07
We manufacture control housings for the oil industry. The steel housings are zinc phosphated then painted with a durable outdoor finish system, an epoxy primer and a polyurethane topcoat. We also have a small parts line where a five stage iron phosphate is applied. The phosphatizing machine is badly deteriorated.
Painting Zinc 03/01/07
We are working on a project that requires the zinc to be colored. I suggested that perhaps we could paint the zinc. I know how to paint, but I am not sure about how to paint the zinc.
Seeds in the Paint Film 03/01/07
We have a coating line in our shop. For one of our customers, we recondition equipment cabinets. After reconditioning, they are stripped and repainted.When we spray dark colored topcoats, we often find defects in the form of seeds on the surface. This doesn't seem to happen when we spray light colors.
Coatings Application 02/01/07
I work in the Technical Center for a company manufacturing gasket materials. We are doing preliminary research into a new type of gasket material. I am looking for someone familiar with coating application techniques. I am hoping you may be able to help guide us on what coating methods to consider as we continue to scale our idea from the laboratory to production.
Conductive Paint On Castings 02/01/07
We specialize in show-quality chrome plating. We are encountering a lot of die cast parts that are corroded so severely that we can't get them to plate. We drill out and fill the pits, but the gray and white corrosion in the metal causes problems. I have been tasked to find the solution to the problem.
More On Hash Marks 02/01/07
I read with interest your reply to B.M., concerning the striations he is getting on his parts that are being dipped. Since he has changed to an air dry enamel, he is using a completely different coating. My first concern would be to look into the flow of the material as it is withdrawn from the dip tank.
Paint Bleed Through 02/01/07
I interpret the question from the December issue to be a problem with the overspray bleeding through at the time of application. The upper and lower panels are usually applied at the same time, with the middle stripe being applied immediately thereafter (or visa versa). This is a very common problem and solved by adding a flow agent (surfactant) to the first coat so the second coat will flow over and absorb the overspray.
Skins On Alkyd Paint 02/01/07
I have a problem dealing with polymerization of an alkyd paint. The paint contains a modified alkyd resin, carbon and toluene. This coating is sprayed on a plastic substrate to manufacture variable resistors.
Clearcoats for Brass 01/01/07
My company produces decorative brass items for outdoor use. The items are not handled after they are mounted on an exterior wall. We polish and buff the items and then degrease them before coating. Our clear coating is an acrylic polyurethane. The brass is oxidizing underneath the coating in within a year of outdoor exposure.
Coating Fabric 01/01/07
I am currently coating cotton fabric with a moisture curing polyurethane for water proofing and abrasion resistance. I would like to switch to woven nylon or crystalline polyurethane fabric but have not been able to get good adhesion. I don't want to use a two-part polyurethane.
Dry That Primer 01/01/07
We are trying a new system to paint steel parts in our paint booth. This involves priming the parts, then painting them as soon as possible in the next section of the booth. We are having problems with getting the primer dry before the paint goes on. We are looking at the amount of primer we use, the type of primer, any additives and the temperature of the booth and the parts. Do you have some insight into this problem?
Paint Test Panels 01/01/07
We recently installed a new paint line and need to send paint test panels to our paint supplier for analysis. He prefers we use surface prepared steel panels three inches wide by six inches long. The supplier's laboratory people know that sample test panels can be purchased but do not know a specific source.
Poor DOI Over Galvanized Steel 01/01/07
I am the engineer in charge of our paint line here in Asia. We make scooters and motorcycles. We would like to improve the Distinctness of Image (DOI) on our motorcycle fuel tanks and seek your advise for the same. The present surface texture is not very good, because the tank's raw material is steel sheet galvanized on both sides.
Wash Primer Again? 01/01/07
In several past issues you stated, "...never, never use a phosphoric acid activated vinyl wash primer over a pretreatment." In theory, this makes sense. I also asked the question, "Why use phosphoric acid on something protected from its action by a pretreatment chemical film?"
Coating Pressed Iron Cylinders 12/01/06
We are setting up a production line for a new product. We want to produce pressed-iron right circular cylinders. We want to paint them using a polyurethane enamel in several colors.
More Waterborne Coatings In Summer 12/01/06
I have some thoughts on the question regarding the sagging of waterborne coatings in the Summer months. As you point out, when we wanted solvent-borne coatings to set up quickly, we could adjust the solvent-balance and/or preheat the parts to drive off the solvents.
Paint Bleed Through 12/01/06
In our plant, we started a production line to recondition 55-gallon drums for re-use by various industrial customers. We paint them black with a white band around the middle. We are having problems with bleed thru while painting them. What are the possible solutions?
Porcelain Enamel 12/01/06
We manufacture heat exchanger components for various industrial applications. In one of our products, we are using a block of cast aluminum as a heat exchanger. To protect the surface from corrosion and mineral deposits from water contact, we would like to try to coat the aluminum with porcelain enamel.
Hash Marks 11/01/06
We paint sheet metal parts in our plant. After cleaning and iron phosphatizing, they are painted on a conveyorized dipping line with a one-coat enamel. We recently changed to a fast drying enamel. Now, we get definite striations on the painted parts.
Humidity Problem 11/01/06
Our paint booth was put in more than 10 years ago at a minimal investment. We now have higher demands to place on it, but we frequently have humidity problems with it. Today, for example, the humidity reading in our paint room is 83%. Many of the specs call for no more than 50% humidity allowed.
Paint Color Shift 11/01/06
We paint our parts in a dip tank filled with solvent based baking enamel. To comply with fire safety regulation, the dip tank is connected to a large underground safety dump tank by a large pipe and automatic discharge valve. We recently noticed our paint use was increasing, so we checked the dump tank and found it full of paint because the discharge valve was leaking.
Painting Polystyrene Insulation 11/01/06
We manufacture pneumatic (air operated) control equipment. We want to lag the air tanks on each compressor unit by covering them with expanded polystyrene bead insulation. We want to paint the insulation to match our units. When we tried to paint them, the polystyrene was melted by the paint solvent.
Spray Can Problems 11/01/06
We are having clogging problems with the spray cans. They are alright the first time, but don't often work the next time. In the plant, we just grab another can, but at the job site, there is often only one can available. What can we do to solve this costly
problem?
Conductive Coatings 10/01/06
We are a custom job shop specializing in "show" quality chrome plating. We are encountering a lot of die cast parts that are corroded so severely that we can't get them to plate. We drill out and fill the pits, but the gray and white corrosion in the metal causes several problems. We've heard of shops coating the parts with a conductive paint and then plating on top of it. Where can I find some information on that process?
Fisheye Eliminators 10/01/06
I read with the problem J. B. is having with fish eyes. I remember when the source of the problem could not be determined, we had a Magic Elixir. It was sold as a fisheye eliminator. A drop or two per gallon chased those nasty fish eyes away. I remember inquiring what the stuff was and was told that it was also some type of silicone that promoted the flow of the coating. What ever happened to this material and was it a type of silicone? It did work.
Testing Clearcoats 10/01/06
I am a chemist at a paint factory. We would like to do some testing for qualification of clear coats. What is the best way of testing clear coats over metal? What are some of the industry tests that can be used? Should it be tested by itself or with a basecoat?
Waterborne Coatings in Summer Weather 10/01/06
I run the painting operations at a plant in the Southern U.S. I am inquiring if there is a general rule of thumb on applying waterbased coatings in the Summer. We are applying a waterbased coating with a robot. The parts first pass through an IR heater set for 650°F, so the parts are "warm" when reaching the paint application area. The issues we see are more drips, runs and sags in the Summer. After doing studies, we can not pin down if it is more relative humidity related, or dew point.
Best Machinery Painting Method 09/01/06
I have a forklift manufacturing shop and searched many years for the best and most economical way of painting this equipment, and finally came to the following method with which I am pleased so far:
- Clean the metal parts with a phosphatizing, rust removing, oil solvent solution applied with a brush, keeping the material on long enough to be wet for at least three minutes. It is recommended by our supplier to be immersed.
- Once dry, rub with a cloth wet with this same solution to remove some fine powder which forms on the surface.
- Now we apply epoxy paint directly with a spray gun, without any primer.
Infrared Reflective Paint 09/01/06
Latex Paint Mechanism 09/01/06
What mechanism(s) causes waterborne latex paints to adhere to their substrates and remain adhered over time? I have some hypotheses and like most physical processes, I'm sure each plays a role in adhesion and a balance exists, but I want to know which plays the largest role. I am also curious about how the change from a liquid during application to a solid film plays a role.
Paint Too Thick 09/01/06
We manufacture durable equipment used out doors. To save energy, we paint our products with air drying paints. We apply a three coat finish system, primer, intermediate coat and a topcoat. Each coat is applied at a nominal film thickness of one mil (0.001 in). The final dry film thickness of the finish system ranges from three to five mils (0.003–0.005 in). One of our customers requested a 10–12 mil (0.010–0.012 in) final dry film thickness for what he considers to be an extreme exposure application. After several days the finish is still soft and has a wavy appearance. What is causing our problem?
Painting Brass Frames 09/01/06
We have a number of brass frames in stock that are not selling well. The boss wants to paint them. They have been in stock so long that they are tarnished. They are both tarnished gold in color and some have tarnished silver elbows. I have never painted brass before and am seeking the easiest/least expensive way of getting it done.
Repainting Warehouse Racks 09/01/06
We recently have been asked to repaint old warehouse racks. They are steel structures. The paint has chipped off in some places and they are showing slight rusting. Is there a good, easily available chemical to clean them before we paint them with an industrial paint?
Automobile Painting Courses 08/01/06
I live in Wisconsin and I know a lot of other states have tech schools that offer auto repair courses. I attended an evening course on how to do basic repairs. Half the course was on repairs. The other half was on painting fundamentals and hands on painting.
Cast Iron Painting Problem 08/01/06
We are just a trading company. We bought some cast iron bathtubs from Northern China in February 2006. They were sent to a customer in Vietnam. Those products are standing bathtubs. The inside is covered with porcelain enamel and the outside is painted. Upon receipt, the customer found all of them to have paint problems-many bubbles formed under the paint layer.
Dip Coating Toothpicks 08/01/06
I am looking for a company interested in helping me on a project to automatically dip coat toothpicks (60% coverage) with a food grade, water-based coating. Can you suggest a place to begin looking?
Gel Coats 08/01/06
I would like to in-mold paint, die or laminate a thermal/compression formed EVA (Ethylene Vinyl Acetate) foam. The foam is used as padding, so the coating must be flexible. Do you have any suggestions?
Loss of Gloss Over Aluminum Bonnets 08/01/06
I am the paint line manager of a company situated in the Middle East. The temperature here gets up to 55°C (131°F). We paint parts for motor vehicles. We have a problem with loss of gloss on painted parts. Why do we encounter this problem of loss of gloss when using waterborne basecoat system on aluminum bonnets?
Painting Galvanized Steel 08/01/06
I am the engineer at a metal fabricating plant. We have a conveyorized line to pretreat the metal, mostly cold rolled steel, before painting in a three-stage iron phosphate immersion system. We have the flexibility to apply most of the coatings available today, including powders.
Painting Stainless Steel 08/01/06
We make decorative products...Some of these are decorated wooden name plates and number plates for the front of homes. These are coated with an oil based enamel paint. We have been asked to make painted brushed stainless steel decorated house name and number plates.
Painting Steel Tubes 08/01/06
Could you please help me to find painting equipment for steel tubes used in sprinkler systems. The length of the pipes is always 20 ft. They are two inches and 10 inches in diameter. The paint is a water based type.
Fish Eye Clear Coat 07/01/06
We're having a problem with our clear coat. Our base coat paint turns out okay but when we started to clear coat, there came the fish eyes. I was taught that if silicone has been used in or around where you were painting this would happen. How can we correct this problem?
Automatic Painting 06/01/06
Our inquiry is about whether we should install an automatic spray coating system for applying a shop primer in our structural steel fabrication facility. This system needs to be able to coat sheet metal and structural profiles in different shapes like I, U and so on. Is automatic coating a satisfactory method to paint these parts or shall we coat them manually?
Automobile Painting Classes 06/01/06
I saw the question from the person who was looking for a legitimate place to learn the art of automobile painting. There is an institute (Name Withheld) that will teach painting, custom painting, etc, but you must also sign up for their auto collision and refinishing course. Unfortunately, I learned that these courses would cost me $28,000 as quoted to me by the institute representative.
Bleeding-Out Issue 06/01/06
We see bleed-out after 2–3 days on our painted parts. The parts are steel substrate and we zinc phosphate and paint them.
Intercoat Adhesion 06/01/06
We fabricate steel enclosures, on a contract basis for equipment manufacturers. We were having corrosion problems. To solve the problem, we upgraded our paint finish by switching to a more corrosion-resistant epoxy primer. We topcoat this primer with the same enamel we have been using for several years. Tests run by one of our customers indicate that while the salt spray resistance has doubled, the humidity resistance has decreased markedly, showing blisters within 100 hours. We never had a blistering problem before. What can we do?
Coating Military Medals 05/01/06
I have inherited my grandfather's and father's World War I and II medals and badges, and I am curious about powder coating them to preserve them for display. Years ago, my father tried lacquer (which failed miserably), then nail polish, which lasted for a few years, then peeled off, as well. They are not particularly valuable, but I would like to have them powder coated clear (after polishing, of course) so they would look good for home display without having to polish them every week.
Paint Over Powder Coating 04/01/06
Can I paint over powder coating? Will the paint adhere?
Painting Stainless Steel Flexible Tubing 04/01/06
I am looking for a method to paint stainless steel flexible tubing for gas and water lines.
Repainting Electrical Panels 04/01/06
We have been asked to recondition and repaint electrical panels. Can you provide the right paint type and specifications for this job?
Coating Interior Surfaces 03/01/06
We have a requirement to apply a liquid dry lubricant product to the inside of an aluminum gun part that is one-inch ID. This coating is a dark gray moly-lube and more difficult to apply than lacquer. Our problem is to find a spray tip or system that will work in this confining space and not result in a course finish. One spray gun supplier tried their 360-degree spray extension in their lab, but we're not impressed and did not recommend buying it. We have the mechanism to advance an extension into the part, but can't find a tip that will perform.
Iron Phosphate High Temperature Performance 03/01/06
I read the question and answer in the Dec. 2005, Painting Clinic titled "Hot Dry-Off Oven Causing Problem". My company paints carbon steel parts with a baking enamel. Before painting, these parts are processed through an immersion paint pretreatment consisting of alkaline cleaning, iron phosphate and seal, with rinses between each step. After painting, these parts are cured in an oven at 300°F for 15–30 minutes. My question is will curing the parts at 300°F adversely affect the iron phosphate coating?
Clear Coats for Bronze 02/01/06
I own a foundry. We cast bronze statuary. Some of our products are fountains with a bronze bowl to hold recirculated water. I need to coat the bowls to protect the finish. We have tried acrylic lacquers and acrylic powder coatings. The standard finishes for bronze won't hold up. These coatings work well on cast bronze but either peel or turn white when used in the bowls within a year. Can you recommend a clear coating that will not peel nor turn white in less than a year?
Inconsistent Gloss Readings 02/01/06
I run a custom coating shop. One of my customers has me painting parts using a MIL Spec two-component paint which we buy from a QPL source. My customer requires a 60-degree gloss reading between 15 and 30. I cannot get satisfactory results from day to day. Some days the gloss is too high, some days it is too low. The paint is from the same kit but reacts differently from day to day. Where do you suggest I look for answers to my problem?
Repainting Aluminum Siding 02/01/06
We distribute aluminum siding. Although most of the product is white, we handle other colors. Sometimes, we are asked to supply more pieces of siding in a particular color than we have in our warehouse. We would like to paint white siding in the appropriate color to fill the order. We have a custom coater nearby who will do the painting. What can we tell him?
Catalyzed Coating Pot Life 01/01/06
How long after a two-component paint is catalyzed can it be used? We are a custom coater and are applying two-component finishes in several colors where high-performance coatings are needed. My painter has been ending his day with several gallons of catalyzed paint left over. I'm old school and hate to throw anything away.
How to Strip Magnesium 01/01/06
I read your article on stripping powder coat paint and it was very informative. However, do you have a recommended way to strip magnesium in a timely manner that will not smear the metal? Abrasive media such as plastic or glass will require a chemical etch according to our overhaul documents and I would like to avoid that.
In-Mold Paint 01/01/06
We are looking for an in-mold paint for polyurethane structures for outdoors use. Our polyurethane structures are window sashes, windows sills, door frames, horizontal beams, some accessories and other decorations used outside the house. We want to use an IMP ( in-mold paint). Do you know of any kind of paint that is compatible with polyurethane?
Silicone Wrist Bands Causing Defects 01/01/06
I have had several people inform me that the colored, fund raising, wrist bands people wear supporting different causes will indeed cause paint defects due to them being made of silicone. I have done everything I can to try to make the wrist bands cause a defect. This includes tying them to racks going through the cure ovens, which showed no signs of defects. Do you have any proven facts about this subject.
Coating to Replace Liquid Rust Preventative 12/01/05
One of our products is elevator guide rails, which are shipped directly to job sites. The machined surfaces of the rails are held to a tolerance of ±0.002 inch and must be protected from rust prior to and during construction. We currently use a thixotropic liquid rust preventative, which works well. The problem is it is messy to handle the rails with this coating and it must be removed before the elevator is put into service.
Coating Glass with Fluorocarbon Coating 11/01/05
We manufacture analytical instruments. We decided to coat one surface of a glass component with a self-lubricating, non-stick coating. I'm interested in trying to find a fluorocarbon coating that I can apply onto a glass surface that will be stable afterwards and that won't leave solvent/grease residues on other surfaces that come into contact with the coated surface.
Corrosion Resistant Coating for Steel 08/01/05
The target requirement for our products is that our refrigerator wrappers and doors need to pass a 500-hour salt spray test without corrosion. The steel will be phosphatized. Is this possible?
Protecting Glass Mirrors 08/01/05
Could you suggest a paint coating or coatings that will protect silvered glass mirrors from corrosion in an outdoor environment?
Galvanized Steel Edge Treatment 07/01/05
I am the manager of manufacturing at our plant. Our plant produces stampings from hot-dipped galvanized material. These parts are being shipped overseas and will be E-coated at a later date. Naturally, the raw edges of cutouts and other edges are rusting due to the corrosive atmosphere encountered during overseas shipment. Our customer has to remove the rust before final coating. We are searching for an inexpensive coating/treatment to protect the edges from corrosion in transit. Any suggestions?
Tacky Spots In Paint Film 07/01/05
We are a shop that specializes in metal fabrication for business machines. We spray a variety of paint types and twice in the recent past have experienced a problem that has us baffled. After a six-stage zinc phosphate pretreatment we spray a polyester...
Epoxy Swimming Pool Paint 06/07/05
We are working at producing a set of water tables for a children's exhibit and are finding trouble applying a coating to these tables. The customer wants the tables painted blue and so we settled on a blue two-part epoxy coating that has some texture. It was applied onto a roughed up surface that was washed according to instructions...
Paint Adhesion on Plastic 05/02/05
We mold and paint plastic parts and have paint adhesion issues. We are not using a primer and apply the base coat directly to the conductive plastic. From what we have tested, there is no variation in the molded part or contamination. Can you tell us what is going on?
Painting Toys Using Waterborne Paints 05/02/05
We have been asked to try water-based paints on our toys, instead of the regular solvent-based paints. Our toys are made using primarily ABS, HIPS and TPE. We want to change because we have odor issues with solvent-based paints sprayed on our toys. Can you please advise what advantages there are in using solvent-based paint on the material we use and why water-based paints are not a good option?
Coatings for Stainless Steel 03/11/05
My company manufactures steel doors. We want to adhere acetate images to stainless steel doors. What can we use as a top-coat sealant for the acetate and long term protection for the doors?
Finish for Chrome Plating 03/11/05
For years, we have been using a modified lacquer as a color coat and for some clearcoat applications on chrome-plated products. The lacquer cured at ambient temperature in about 14 days and could be forced at 170°F for 30 min. We are unable to buy the product any more because the supplier withdrew it from the market and we are looking for a company that may have something that will meet some interior automotive specifications...
Plural-Component Coating 03/11/05
I read your comments recently about the use of plural-component coatings with reference to applications requiring such coatings prior to dye sublimation applications. We work in dye sublimation and would very much like to coat our substrates "in house" if possible. We have some spray capability and feel this would greatly enhance our product line, since "coated substrates" are very limited with reference to design application...
Adhesion of UV-Cured Ink to UV-Cured Coating 01/10/05
I am a printing shop supervisor searching for a UV-cured ink, which can be printed onto a metal substrate that has been powder coated with a polyester paint. Is there such an animal? Would a UV-cured ink stick to a UV-cured powder coating?
Painting Plastics 01/10/05
Could you provide me with more information on non-metallic coatings on plastics, like plastic coatings on a plastic substrate? What is the process? Thank you for any help and/or advice that you can give.
Paint Selection Guide 11/19/04
I would appreciate seeing a chart describing typical coating groups, the relative VOC/HAP content, approximate film range, typical percent solids, inherent characteristics and typical applications. Can you point me towards such a generic chart or can I hope to see such a summary in a future article?
Paint Compatibility 11/09/04
With regard to the question "Painting Cast Iron Valves" sent in from P.J., there are so many unanswered questions in my mind concerning his high rework rate that he says is close to 100%. It may sound strange, but I could feel the frustration in myself in not being able to evaluate his set up and solve his problem. Since he is using a two-part epoxy system, he probably does not have to be involved with any heat or low heat and therefore would minimize out gassing...
Painting Cast Iron 11/09/04
We manufacture water features for fountains, pools and ponds. We are starting a line of cast iron products. Since part of the feature will be submerged, what is the best way to protect a cast iron water feature from rusting? In some cases some of our customers use these products in water containing fish. Also, is a non-toxic-to-fish paint option available?
Vinyl Caps for Wire Ends 11/09/04
We use a piece of heavy gage wire in one of our products. We are looking for a replacement for a hand applied vinyl cap. Applying this cap is labor intensive. The cap covers the cut end of the heavy gage wire. The cap protects the customer from a burr and provides a finished look to the wire. Do you know of a product that could be used as a replacement for this cap and be applied in liquid form for dipping the wire end?
Non-Visible Infrared/Ultraviolet Paint 09/25/04
Here at our Automation Technology Laboratory at the University, we've been using "landmarks" for mobile robot navigation. The landmarks are actually printed black and white images attached to the ceiling. The robot has a camera and a computer vision system is able to localize the robot using the landmarks. The problem is, the landmarks are considered unaesthetic by some people. So the question is: Is there a paint that we could use to paint the landmarks so that they would not be visible to humans? We were thinking of using infrared-absorbing (or reflecting) paint and an IR-camera. Black paint would absorb well but is visible. Does paint that only affects non-visible frequencies exist?
More on Painting ABS Plastic 09/23/04
I am responding to your July 2004 column about "Painting ABS Plastic." I agree with your basic premise to use a slower solvent. My company probably would cover both routes by blending mineral spirits equal parts (good for oil contamination) and butanol (good for finger prints and stearate type mold release)...
Painting Cast Iron Valves 09/23/04
We are a manufacturer of cast iron valves. Having just joined the company in a QA capacity, I am alarmed at the poor quality of our paint finish and the sheer number of customer complaints with regards to this. We use a two-pack epoxy on top of a primer. We receive our castings from the supplier in a primed condition and wash them down before topcoating. In some circumstances we have grit blasted the castings prior to topcoating; the appearance of these valves is much improved but I am unsure whether the paint finish is more durable with a better key...
Coefficients of Friction 09/01/03
I need to identify a material with a high coefficient of friction that will not scratch a painted mortar surface. The surfaces in contact are the mortar painted surface and elastomer or other material being pressed against the painted surface with a normal force of about 200 foot-pounds...
Wrinkle Finish in Custom Colors 09/01/03
I have a need to create a wrinkle finish in custom colors. Over coating gray wrinkle causes a loss of detail and is subject to scratches. In my conversations with a multitude of companies, one suggestion is to add cobalt naphthenate or some other surface accelerator to the paint mixture as a top layer drier to dry the surface faster than the lower layers of paint.
Melamine in Automotive Paint 08/01/03
Our plant is located in South Africa. I am curious about melamine in automobile paint and the way it is being used in the automobile factories...
Magnetic Powder Coating 07/01/03
For the person who was inquiring about a magnetic powder coating, the following reader response was offered. Kling Magnetics, Inc. (Chatham, NY) makes a liquid paint that is considered to be compatible with magnetic devices. Its web site is www.kling.com...
Military Specifications 07/01/03
I am a technical consultant who has assisted a small business in being awarded a government contract for Zn phosphatizing (TT-C-490D) and priming cylindrical forgings. The primer callout is MIL-PRF-23377G, Type I, Class C, (epoxy/catalyst, 4:1 mix, two part kit) to a minimum primer thickness of 0.0005 inch and combined Zn phosphate/Primer thickness of 0.0050 inch. Where can I find "technical application information" for applying this primer to steel? Can you point me in the appropriate direction?
Multi-Color Finishes 07/01/03
Way, way back, about 30+ years, I remember that there was a coating that when sprayed resulted in a "multicolor" spatter finish. At that time, I inquired how that finish produced two colors at one time when sprayed. I found out that the material consisted of two incompatible coatings, probably one a lacquer and one a latex material. It has been quite a while since I have tried to recall the blend. (I don't think that the second material was an alkyd since I suspect that the two would blend.) These two remained separated when atomized. At this moment I can't think of the trade name used. Do you remember what it was called and what the blend was? I wonder if this coating is still made? Thank you for a wonderful, informative column...
Painting Stainless Steel Alloy 304 06/01/03
I would like to know if it is possible to paint stainless 304 with a high solids epoxy type paint (per Mil-C-22750). If not, can you recommend a paint type that would be more suitable for this alloy. What type of primer is recommended for this surface? Also, is it possible to achieve good adhesion without any mechanical abrasion to the surface, and if not, would abrading the surface compromise the corrosion resistance properties of the stainless steel. We would prefer to prepare the surface for painting by cleaning with degreasing solvents, but will this ensure good primer adhesion?
RansPrep!! 06/01/03
Nick, thank you for your informative magazine. I currently work for ITW Finishing, formerly ITW Ransburg, formerly Ransburg/Gema, etc. RansPrep is still available from a company called Chemical Technology. They can be reached at (313) 893-4930. Formerly this company was called Electrocoat Chemical and HSC. Corp. Let me know if I can help further.
Bulk Painting Split Rings 05/01/03
The company at which I am employed produces split rings that are used in the manufacture of fishing tackle. The rings are used to attach hooks to lures. We are looking for a way to apply a color finish to these rings which are durable enough to withstand the conditions which they must endure...
Painting Over Zinc 05/01/03
I currently manufacture a part out of cold rolled steel. The part then goes to my plating source. They rack plate the part (zinc plate). The part then moves to my coating source and they paint over the zinc plating. The problem is that when the parts get back to me they are covered in a rough bumpy coating. This is not acceptable to my end item customers. My plater and coater don't seem to want to help. They just want to point fingers at each other...
Plastisol Drips 05/01/03
Just read your comment and response to C.O. in the January 2003 issue, Re: Plastisol Drips. I'm with you. We prime and plastisol coat small hardware on an automated machine. The parts are not touched once they are racked up and automatically proceed through the primer dip, pre-baked, plastisol dipped and then post baked...
Topcoat For Plastic Reflectors 05/01/03
I work for a major manufacturer (made in the USA) of emergency warning lights for fire trucks, ambulances, and police cars. We mold our own reflectors out of Polycarbonate, Amodel, Lexan, Apec, and Ultem and have them metallized and coated by a subcontractor...
Plastisol Drops 02/01/03
Although we wouldn't presume to usurp the formulating expertise of a coatings manufacturer nor the expertise of the experienced user, the item in your July 2002 column piqued our interest...
Colloid Chemistry 101 10/01/02
Just a comment on your answer to the question on applying Teflon coatings. I am fairly confident that there are no liquid Teflon coatings that are emulsions. They are all dispersions of the Teflon powder in a liquid medium (water or solvent based). Emulsions are mixtures of two non-miscible liquids-one being emulsified in the other. Teflon does not exist as a liquid at room temperature. Also, Teflon is a registered trademark of the DuPont Co., and DuPont is the sole manufacturer/supplier of it.
Adhesion to UV-Curable Powder Coat 06/01/02
I am a printing shop supervisor searching for a UV ink which can be printed on a metal substrate powder coated with a polyester. Is there such an animal? Would a UV ink stick to a UV powder coat?
Durable Coatings for Aluminum 06/01/02
I'm bidding on a job requiring powder coating aluminum windows (the interior side) on site in an apartment building. That does not seem to be possible re: heat curing. So what would be the best finish for repainting, preferably by spray painting? I want something extremely durable and available in a wide range of colors and finishes. It's a very high end job...
Heat-Resistant Paint 06/01/02
I hope you can help with my paint question. We just moved into a house with a fireplace that has a round metal chimney that goes up two-stories to the ceiling. Apparently, the previous owners used the wrong paint or process to paint this chimney white, and with only a couple of months use now, the paint is cracking and peeling...
Thermochromic Paints 06/01/02
In the July 2001 issue you wrote about thermochromic paints. I am also searching for a thermochromic material that meets these specified requirements. Is there any chance I could get in contact with the sender of this message or could you give him my e-mail address?
Putting the Shine Back on the Gloss Problem 04/01/02
This may be of interest regarding (NH4)2CO3, which is ammonium carbonate. When trichlor or perchlor or any other halogenated solvent gets into a direct-fired oven, the solvent breaks down in the flame to produce hydrogen chloride, also known as hydrochloric acid. This acid can greatly affect gloss and even the texture of wet paints...
Non-Paint Painting 03/01/02
This is written regarding your November 2001 clinic piece on staining oak fences. First, unlike painting, which puts a solid color on the surface, staining adds transparent to solid color to the wood grain. The application of a stain is called "staining." All stains, especially those used in exterior applications, require a topcoat to protect the surface of the wood. Topcoats may be varnishes or lacquers. Uncoated exterior wood stains will discolor, and the wood will deteriorate quickly, especially oak...
Non-Painting Alternatives 03/01/02
I am the director of product development for a company allied to the finishing industry. May I suggest some alternatives to your answer to a reader's request for a "non-painting" alternative to painting wood fencing, which appeared in your column in the November 2001 issue...
Painting Concrete 02/01/02
I am looking for a product that will effectively adhere to cement under tough conditions. This coating will be subject to steamy boiling water. There is an expansion joint as well as the cement that must be covered and protected.
Two-Component Coatings, Part II 02/01/02
These remarks are in reference to your October 2001 clinic question on two-component coatings. My company supplies a lot of 2K systems in low/satin gloss. You are correct that changing the catalyst/hardener ratio can cause a difference in the performance properties. The coating will likely cure as the leftover isocyanate will react with the moisture in the air...
Acid-Free Finish for Brass 01/01/02
I am looking for a finish to apply to brass so it will not tarnish, but the finish must be acid free. Because the brass pieces will be used with archival pictures and documents, the finish can in no way compromise the archival process. I would appreciate any advice you can offer.
Here's a New One for You 01/01/02
In a recent issue of PF, I read your comments on the dampening of sound on springs. I thought of a product that I recently saw applied to springs by a unique process. With this process, parts are quenched in a water-based coating directly out of heat treatment, stress relieving or tempering (whichever is last in the process)...
Dye Sublimation Coating 12/01/01
I am looking for a supplier of a clear polyester type coating to be applied over a glazed ceramic substrate (tiles, mugs, etc.) to which I will then apply an image using dye sublimation...
Thermochromic Paint 12/01/01
I am the owner of a custom painting shop. We custom-paint racing and motorcycle helmets and motorcycles. I recently had a customer ask if I could paint an entire motorcycle with thermochromic paint. I know very little about this type of paint so I don't know if this is possible...
Non-Paint Painting 11/01/01
I'm trying to determine the best way to finish my 1,500 linear ft of oak 3-board fencing. We want to make it black but don't feel that paint is the answer. Do you have any good suggestions?
Reflection on Iridescent Coating on Aluminum Mirrors 11/01/01
In the January 2001 Painting Clinic, I answered a question about iridescence in ultra-thin coatings applied to aluminum mirrors. The question posed by J.C. was as follows: "I try to deposit a thin layer of varnish (5-8 microns) onto an aluminum mirror. So far I have had some problems since I see iridescence once the coating is dried, even with a thickness up to 15-20 microns. How can I solve this problem? Thanks for any help."
Resins in Liquid and Powder Coating 11/01/01
I should like to have more information on powder coatings available as liquids for painting electrical panel boards and other steel furniture that is fabricated by us. If you could please send us some materials or pointers regarding these, I shall be very grateful.
Zinc-Rich Coatings 11/01/01
I read an article some time back about the relative merits of zinc-rich epoxy coatings vs. inorganic zinc coatings. I can no longer find the article and am hoping you can help. The gist of the article was that zinc-rich coatings, which do not have the zinc flake overlap of the inorganic zincs, performed equally well due to a chemical reaction of some sort. Can you confirm this?
Black Nylon Powder Coating 10/01/01
We have a custom coating shop where we apply paint as well as powder coatings. We are in the process of considering bidding on a job that calls for a black nylon powder coating. We have never used this material and are not familiar with it, but believe we can apply it. Could you tell me more about this type of paint and the usual applications where it is used? Also, where can it be purchased? R.B.
Clear Coat For Galvanized Steel 10/01/01
Our company is the leading fence and mechanical tube producer in the Caribbean basin. The above-mentioned markets call for an additional coating that is well known as a "lacquer." This type of coating protects the tubes generally stored in a yard exposed to several weather conditions such as rain and dust which are conducive to white rust at early age.
Two-Component Coatings 10/01/01
I need literature on high gloss problems concerning liquid paint and conventional oven curing. We are having gloss fluctuation with the liquid paint. Parts are not coming out of the oven at consistent gloss levels. The mixing ratio of the paint has been checked and doubled checked. There is no mixing problem that we have found.
Corrosion Protection 08/01/01
I am trying to stop corrosion on a high carbon steel. The steel is a track for a tool on a water jet system. The tracks themselves are about 4 inches wide, 1 inch tall and 30 ft long. The track is one solid piece and can't be cut due to the 0.002 inch tolerance that is required. The water jet runs city water mixed with an abrasive-garnet. The garnet was tested for the metal content. It was found that the only metals that appeared in significant amounts were aluminum, 7.455 ppm, and iron, 20.83 ppm. I am looking for a possible coating to use to prevent any further corrosion.
Film Defects 08/01/01
What is cissing? Does this appear in polyurethane paints specifically? How can this condition be corrected? Is there some additive that can be used to solve this problem?
Painting Metal Products 08/01/01
My sons and I are partners in a small family business in which we do custom metal work, welding, painting, polishing, etc. We have tried to powder coat all of our products, but the cost is very high and we do not do enough volume yet to justify the high cost of large-scale powder coating equipment. We have a 200-item order for mailboxes, posts and brackets. The posts and brackets are made of 4×4 square tubing; we form the mailboxes out of 16-gauge steel. Because of the price of our bid, I cannot afford the $60 to have each one powder coated. Is there any mixture of paint that I can use to come close to the durability and hardness of powder coating? We use both oil based enamels and automotive paint.
Polyurethanes vs. Epoxies 08/01/01
I would like to know what the differences are between epoxy and polyurethane coatings. I have been an applied coatings technician for 15 years and had never given it a second thought until my boss somehow ended an unrelated argument with that question. I was instantly baffled. Apparently no painter has ever been able to give him an answer. I am aware of the different applications of each coating but do not know why or what determines it. What are their characteristics alone and used in conjunction with each other? My boss would be as enlightened as I would if you could shed some light on this topic.
Black Coating for Aluminum 02/01/01
I am doing some research on the full range of potential coatings and associated application methods to apply a uniform black coating to the surface of an aluminum automotive condenser product. "Normal" spray techniques, for both liquid and powder, and the associated ovens and material handling equipment, are very expensive and labor intensive. The product will be somewhat amenable to IR heat processing or IR/convection combination. The coating will need to withstand fluids, such as windshield washer fluid, without degradation along with some heat tolerance, similar to that under the hood of a car. I was wondering if you could shed some light on the subject from your experience with any coating(s) and/or inks that might be a good fit for the product and also further my knowledge of what is available in industry to get a uniform black appearance on a product in a simple, inexpensive way? Thank you for your consideration.
Painting Molded Polyurethane 02/01/01
Do you have information concerning the painting of urethane? The urethane is thin-skinned with a grain surface. I need to know what type of paints can be used? Does urethane need to have a cure time prior to painting? What solvents can be used to remove mold release? Thank you for any assistance.
Painting Over Gold Plate 02/01/01
We are in the eyeglass business. My question involves both plating and painting. We have a clip-on, which is made of a brow bar and two sets of clips. A lens is cut out to a lens shape, and then the brow-bar is placed over the lens and crimped on with a pair of pliers. The same thing is done with the lower clips. My problem is that the brow bar is gold plated and the clips are black. We currently have these parts made overseas but wish to have a back-up process here in our shop, if things take off. The clips are small; the brow bar is only 0.040 inches in diameter and has to flex without the paint flaking. That's the easy part. Now, the ends need to be masked and painted black with no paint inside of the clip. The clips we plate and then paint over always seem to chip. I believe painting the clips first and then gold plating would be better. Our challenge is that we don't run millions of pieces, and buying masks for painting seems to be costly. I appreciate your thoughts on a solution to this problem.
Trends in Painting 02/01/01
What are the trends in the paints and coatings industry regarding what types of products are painted (for example, mobile phones)? What are some of the latest high-tech coatings? Which technology amongst the industrial coatings sector has the largest application? I need some information about the European market for decorative paint. I'm also interested in figures (sales, largest companies, equipment investments, etc.) for the industry globally for 1999.
Controlling Water Soluble Enamel 11/01/00
The coating process used in our facility is a flow through system using a water soluble enamel. We are having an issue with inadequate coverage of frame assemblies. The parameters being monitored currently are the pH of the wash, rinse and paint; the viscosity of the paint; and the temperatures of the wash system and dry-off and bake ovens. What other factors are significant in controlling this type of coating process?
Durable Clear Coatings for Brass 11/01/00
Our company makes a wide range of brass architectural products, such as hand railing, public guidance posts and kitchen household fitting. We purchase clearcoated tubing and extrusions. What are the most durable clearcoat processes currently available? We are wondering if there are new technologies available that would improve the durability of our product.
Making Wrinkle Finishes Wrinkle 11/01/00
Getting a good wrinkle finish is just about as easy as painting with any aerosol type finish. It is important that certain rules be observed.
Painting Plastic 11/01/00
We are trying to paint a cover made of Cycolac ABS plastic. We are using a two-component polyurethane paint. Our problem is that we are experiencing a "blemish" on a cosmetic surface. The blemish is being caused by either the mold or the mold release. Is there anything that we can do to either hide or prevent this problem besides applying a barrier coat or sanding?
Painting for Infrared Measurements 11/01/00
We paint bare die electronic assemblies to create a uniform emissivity in order to perform infrared camera thermal measurements under power. Without this process, surfaces with low emissivities would appear lower in temperature than a high emissivity surface at an equivalent temperature. Can you recommend a paint for this application? It should have very low ionic content so as not to cause shorting or current leakage on the bare die and substrate surfaces? Other desirable characteristics would be stable properties at temperatures from-40-200C, availability in aerosol can form, fast drying, black color, ability to be applied in thin films and good adhesion to SiO2 die passivation layer. Thank you for any assistance you can provide.
Blistering on Recoat 10/01/00
We paint our steel enclosures before assembly, and the painted enclosures are stored. We often have to rework these enclosures because of paint chipping and scratching during handling. We are getting blistering of paint when we re-apply paint over ASA 61 gray baking enamel. Before repainting we apply a tie coat. We then re-apply our ASA 61 gray baking enamel. The finish comes out like a reptile. The epoxy is an air dry. What is the best tie coat? We cure at 315-330F. Our line runs at 10 ft/min. Thanks.
Chalking of Heat-Resistant Paint 10/01/00
I have a customer who manufactures and paints fire rings, which are used at parks and campsites around the country. They use a heat resistant paint rated to 500F. In our testing, we found that the coating can go at least as high as 750F, however there is some "chalking" of the coating. We're wondering if this chalking is normal for high-temperature applications. Thanks for your help.
Adhesion to Plastics 09/01/00
Recently, I have experienced some sporadic paint adhesion failures. My substrate is plastic and the topcoat is a low-solids 1K/2K solvent-borne technology. The adhesion failures occur between substrate/primer and the primer itself (splitting). I checked the power wash with the supplier to ensure the detergent/virgin DI water performs within specs. Everything checked out. My bake chart checked out with proper part temperature as recommended by the paint supplier. The failures occurred across different colors. Can you suggest anything else I can do eliminate the issue? I also use another paint supplier for other product but experience no problem. There is no contamination between the two suppliers. The substrate that has adhesion problems is molded in-house. No release agent is used at all for these parts.
Finish for Stainless Steel 09/01/00
We are looking for a navy blue finish for a 304 stainless steel cylinder that is used as a knob on one of our products. This cylinder has a counterbore at each of its faces. Ideally, we would like the color to match that of our 2024-T4 aluminum blue anodized part, which is the same part but in a smaller size. The stainless part has a diameter of 1.25 inches and a length of 0.760 inch. A band of knurling 0.25 inch wide encircles the cylinder. If the finish adds any thickness, then we would need one face and the inside of the part masked to avoid any tolerance issues. We desire this finish for purely aesthetic reasons, but we would need something durable enough to be pulled on periodically. Any insight you could provide would be greatly appreciated.
Electrical Insulation 08/01/00
I work with a consulting firm and I am doing research on finishes. I am trying to figure out if there any finishes that are used for insulation purposes. If so, then which markets are they used in and how are they used (for example, automotive for coating engine blocks or electronic for coating microprocessor chips). Any information regarding this topic would be helpful.
Black Finish for Aluminum 07/01/00
I am a technical salesman for a coatings supplier in the Chicago area. After reading your Q&A in the March edition of Products Finishing, I would like to comment on the question regarding Black Finish for Aluminum. My company manufactures cookware coatings as well as functional coatings for the industrial market. We supply black thermoset coatings that are completely durable against abrasion and corrosion from salt water conditions. There has been a great deal of competition in this area of the fluoropolymer coating industry, which has led to the availability of coatings of all colors and VOC specifications.
Metallic Finish on Wrought Iron 07/01/00
I am from India and have just begun a small workshop to make and design wrought iron accessories. So far, I have only been painting enamel paints on the metal. So, now I need help from you regarding a particular finish. The finish is dark gray with a metallic luster. I am attaching photos of the pieces that have the particular finish I am seeking. What I actually need is the recipe or method to achieve this finish. Since I live in India and will be unable to see you there, I am forced to seek your kind help in this manner. Your help would be a great favor.
Thermochromic Paint 07/01/00
I need some help. I am looking for a thermochromic paint that is reversible and has high-temperature capability. The only product I have found is low-temperature, 59 to 131F for color change, and an upper temperature limit of 300 to 350F. I need a paint that will color change at 140 to 170F and can survive 850 to 950F for 10-hr periods and still reverse color after 500 to 800 cycles. I had a sample 6 to 7 years ago that would change from red to black and survive on a 1,000F vitreous surface. Has anyone out there any information on such a product?
Black Finish for Aluminum 06/01/00
The original question from G.B. was, "I have instrument display bezels machined from 6061 aluminum plate. They are then engraved with a logo and lettering, then painted black. Because of the operating atmosphere, being a drilling rig in offshore waters, the paint gets scratched or damaged. I have tried black anodizing and found that it fades when exposed to sun and sea mist. I am asking for suggestions for a black finish that is tough and durable."
Unknown Resins in Old Paint 06/01/00
I am an analytical chemist by profession and an industrial consultant. I quite eagerly look forward to your column each month. I often encounter paint problems and your column is a wealth of information. I have been asked by a local manufacturer (I live in southern Ontario) to prepare an MSDS for an old stock of white primer, which they would like to use. I have data on all the components but two, the alkyd resin and a second component. The company that blended and sold the paint has gone out of business, and we have tried numerous suppliers with no success. If you could point us in any direction it would be greatly appreciated. Thank you for your efforts.
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