Coating PVC Products

Q. My company manufactures small plastic items, many of them made using parts molded in various colors. One line of products is fabricated from black PVC irrigation pipe. I would like to be able to offer these products in colors other than black. The coating must be abrasion-resistant enough to withstand metal and plastic objects sliding across its surface without scratching. M.W.

A. I am sure you are aware that many paint solvents will attack PVC pipe and cause anything from surface etching to softening and distortion. However, there are a few solvent-thinned paints that can be used on PVC. I have used some of these on plastic structures for my model railroad without damage.

It is best to protect the PVC from solvent attack using a waterborne coating. Then you will be able to apply an abrasion-resistant coating. To coat the PVC parts without destroying them, you have two choices:
1) Apply a two-coat finish consisting of a waterborne primer topcoated with a compatible epoxy or polyurethane enamel in the color of your choice.
2) Apply a one-coat finish consisting of a water-reducible epoxy or water-reducible polyurethane enamel.

These are industrial coatings available from paint companies.

There is a caveat, however. Since some waterborne paints contain co-solvents that may attack the PVC, test them before you buy them. I have seen a line of spray paint advertised as specifically formulated to paint plastics that can be purchased from Big Box stores, but I have not tried it. These spray paints may coat PVC without damage, but I don’t know anything about their abrasion resistance. It may be worth trying on your PVC products. Otherwise, I suggest you contact your local paint salesman or the industrial sales department of a paint company for their recommendations.