We have a small shop where we produce stainless steel kitchenware such as plates, cups, flatware etc. We would like to add to our line by offering decorated items. This would consist of painting fruit, scenes or other decorations on the stainless steel surfaces. I saw the question regarding painting the stainless steel medicine cabinet in the April 2002, Products Finishing magazine. What can I do to them after I prep them as you mentioned, in order to use a few different colors? Does the two-component epoxy enamel come in colors? Do I need to seal it when I am done to protect it so the item can be used? Thanks for your help. J.B.
There are many excellent plastisols on the market, which when applied appropriately, do not exhibit sag or drips. We strongly recommend that your reader contact his plastisol manufacturer to request a solution to his problem either in the form of process improvement suggestions or a change to a different plastisol.
The key to a no sag/drip plastisol is the use of an appropriate sag control agent incorporated into the original formulation that is stable and predictable across the entire use and cure cycle of the plastisol. Many plastisol producers use colloidal silica or organic treated clay additives and achieve a fair level of success with this challenge. To achieve the highest level of thixotropic viscosity control over all of the temperatures the plastisol encounters, my company recommends the addition of a couple of its additives at a level of about 1-3% . This must be added at the plastisol manufacturing step by the coating supplier. In short, the end user must demand a high-quality product that provides the performance he needs at a fair price. S.R.
As I told T. H. in the April Painting Clinic column, stainless steel is relatively inert; hence, paint adhesion could be a problem. Paint adhesion to stainless steel can be enhanced by using pretreatments. In your case, you don’t want to use a pigmented primer because it would cover up the stainless steel substrate. You can successfully decorate your product by following these directions:
1. Degrease the stainless steel using a hot alkaline or detergent cleaner (a hot aqueous solution of dishwashing detergent will also work)
2. Rinse completely with clear water and dry.
3. Roughen the surface using sand paper, plastic abrasive pads, abrasive blasting or whatever abrading device you have. It is important to note that wire brushing is not a good choice because it may leave steel particles embedded in the stainless steel surface that could result in rust spots.
4. Apply a two-component epoxy enamel, which is available in a multitude of colors at paint stores. The epoxy will have the best adhesion of any commercially available paints. Mix the coating material according to the suppliers instructions and apply by brush rubber stamp or spray to the cleaned and pretreated stainless steel.
5. Allow the decorated parts to dry in accordance with the paint suppliers instructions.
That’s the good news. The bad news is that if the stainless steel is used as dinnerware, the coating can be removed by the repeated use of knives, forks and spoons. It will not be as durable as decorated china and ceramic dinnerware. You could apply an overcoat varnish to protect the decoration using a clear two component epoxy. This will provide temporary protection and will, in effect, only prolong the inevitable.