Ask the Expert: For fleet refinishing, do I need an adhesion promoter when I am painting plastic?

Q: For fleet refinishing, do I need an adhesion promoter when I am painting plastic?

Dan Szczepanik, Global Product Manager - Fleet & Manufacturing, Sherwin-Williams Automotive Finishes: Plastics can be split into two groups: polar and non-polar. These words describe the surface of the plastic. Think of polar plastics like water and non-polar plastics like oil. Most coatings and primers are on the polar side (even solvent borne coatings) of the scale and adhere fine to polar plastics like ABS, polycarbonate or blends of the two plastics. No special primer is needed, and often top coats can adhere directly to these plastics. Problems can occur when you are painting non-polar plastics like polypropylene (PP) or polyethylene (PE) or any olefin (think oil) containing plastic, and you did not identify them correctly. These non-polar plastics need a specialized adhesion promoter. An adhesion promoter has one half of it designed to stick to the non-polar plastic, and the other half designed to stick to paint applied over it. It acts like a zipper to join the above primer to the below plastic. It’s a very useful product, and when used over non-polar plastics, will ensure the repair stay in place for years to come.

Information provided by: Sherwin-Williams Automotive Finishes