Choosing Cleaning Wipes for a Specific Process
There are so many different cleaning wipes on the market. MicroCare’s Mike Jones offers some information to help you choose the right ones.
Q. We use cleaning wipes for an array of tasks, but with so many different options on the market how do we know which type to choose?
A. Cleaning wipes are used in almost every type of organization and industry, including product finishing, as they are so versatile. There are so many different wipes on the market it can be like treading a minefield to choose the right one for the job.
In general, there are three broad categories of wipes: non-woven wipes, woven or knitted flat wipes, and swabs. To choose the correct wipe for the job first consider, the absorbency needed for your contamination, then think about the contamination you are cleaning.
Absorption is usually expressed in milliliters of water or alcohol absorbed by one square meter of the material. Some wipes work well with solvents or lacquers but will not absorb water. For example, polyester is petroleum-based, so polyester wipes easily absorb gasoline, oils or grease. Cellulose wipes are good for water-based contamination.
In general, fabric wipes tend to be more absorbent, stronger and durable. Although they may be more expensive to buy, they generally work out to be less expensive to use. Paper wipes are often used in applications in which re-contamination cannot be allowed, such as in electronics and medical applications, and are usually single-use disposables.
Believe it or not, cleanliness of the wipe is also crucial to the end result and is measured in particles per square meter. Cleanliness is inversely related to absorbency; the cleanest wipes may be less porous and unable to absorb as much, while more absorbent materials may leave fibers or residues.
The packaging itself also deserves some scrutiny, it should be free of particulate, with no fibers, plasticizers, silicones or ionics. Another feature appreciated by engineers is static-dissipative wrapping which will not attract dust.
Cellulose wipes are the cheapest non-wovens and use glues or binders to hold the fibers in place. Most binders will dissolve when exposed to solvents, so wipes made with binders are undesirable for critical applications. They will leave adhesives, lint and fibers on the surfaces being cleaned, especially when wet. Most cellulose wipes simply are insufficiently strong, clean and absorptive to handle anything but the simplest cleaning tasks.
In the middle price range are non-wovens made from synthetic fibers like polyester and polypropylene. Textured polypropylene wipes pre-saturated with a d-liomene solvent are ideal for cleaning grease and heavy oils.
It’s hard to imagine how a simple paper wipe could be strong enough and clean enough to be useful in industrial situations, but paper manufacturers have developed a hybrid material called a non-woven fabric. This premium-priced material has the strength, softness and quality of a woven textile, but is produced at the volumes, speeds and cost of a paper.
Woven and knitted wipes come in a range of materials, qualities and prices. The least expensive material is reclaimed fabric. A better choice is a mill end fabric, but they can be loaded with permanent press chemicals, stain-resisters and dyes, and so can increase contamination issues. The next level is washed cheesecloth, but it is very hard and stiff, completely unsuited for wiping, although, after a thorough washing with special surfactants and detergents, the material becomes very smooth and flexible. Nearing the top of the quality pyramid is “washed diaper fabric.” This material is soft, strong and highly absorbent, but can be expensive.
If clean-room performance is essential, opt for knitted synthetic fabrics of polyester or rayon. These materials are soft, clean, absorbent and lint-free, making them the leading choice if high cleaning results are required.
Another choice are swabs, which are basically wipes on sticks. The stick allows the swab to tackle jobs an ordinary flat wipe could never handle. The key to selecting a swab is the design of the head.
Cheap cotton fibers make the least expensive swab but are fairly “linty.” Reticulated foam makes a good swab for scrubbing but tends to leave particulate residues. The highest quality swabs are made from prewashed knitted fabric, but they come at a price.
The manufacturing processes used to produce each swab makes a difference. The better grades don’t use adhesives to hold the swabs together, so any solvents used in the cleaning process will not dissolve the adhesives and leave residues. In contrast, many adhesive polymers, which are quickly dissolved by solvents, may cause problems downstream in a manufacturing process.
While absorbency is critical when selecting a swab, a unique issue is materials compatibility. The construction of the swab must be compatible with the cleaning application. For example, if acetone is used on a foam swab, the foam tip will swell and weaken. In applications where acetone must be used, a polyester swab is by far the better option.
The Latest Arrival: Pre-Saturated Wipes
Another option is the pre-saturated wipe. It offers the right fabric and solvent in the correct combination, resulting in a more consistent cleaning performance. There also is a time-saving enhancement, as these wipes come ready-to-use. A broader array of cleaning fluids, both water-based and solvent-based, have enabled manufacturers to tailor their pre-saturated wipes for different environments, and better packaging has allowed some companies to offer pre-saturated products with an unlimited shelf life. All in all, there’s time to be saved and money to be made by switching to pre-saturated wipes in many applications.
The optimal cleaning fluids for pre-saturated wipes are water-based with soaps, alcohols, hydrocarbons or siloxanes. Stronger fluids, such as d-liomine, will attack the plastic tubs. Fast-drying solvents are rarely used because they will not deliver the required shelf life. Good toxicity ratings (TLV of 200 or higher) are generally a prudent strategy.
Two tips on pre-saturated wipe packaging: First, insist on a self-closing lid so the liquid does not evaporate from the tub, and secondly, look for companies that make refills. The tubs themselves can last quite a long time, so it makes sense to save money and protect the environment by re-using them. This can save companies 30 percent or more over purchasing new tubs.
Mike Jones is vice president at MicroCare Corp. Visit microcare.com.
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