Ask the Expert Question-and-Answer Archive

by Ron Joseph

May, 2005

Automotive Clearcoat Poor Performance

Q. I have a 2000 Toyota Sienna [white]. I am the original owner and never had body or paint work done on this vehicle. I noticed that the paint on the tailgate and rear and frt. roof panels look really dull. I take good car of my cars and I wax them and garage them regularly. Having been a Chevy dealership service manager for many years, I am very familiar with poor paint quality. I am however, very surprised to find this on a Toyota. It appears as if the clear is worn or weathered away. Any thoughts?

A. It is entirely possible that, as far as the clearcoat goes, you've got a lemon. I hope that when you polish the car you are not using any hard abrasives that might have caused this problem, but my guess is that the painters at Toyota didn't get to these areas with adequate film thickness. The problem with applying a clearcoat is that painters can't see how much coating has been applied. Quality control is not perfect, even at an automotive assembly plant, and there are no QC tests that immediately point out thin areas of the coating. Unless someone at the QC inspection station had specifically measured the film thickness on your car at those locations, nobody would have seen the problem.

In some automotive assembly plants robots apply the clearcoat to most of the car body, but painters manually pick up those areas in which the robots are known to be lacking. Alternatively, one of the robots might have had a blockage or might have been starved of clearcoat while it was traversing your car. These are simply thoughts that come to my mind to explain why you might have a faulty paint job.

Without seeing your vehicle and measuring dry film thickness using nondestructive methods, I can only assume that a robot or the painter(s) were at fault. Because of the excellent abrasion resistance of automotive clearcoats it is less likely that your polishing is at fault.

Best wishes,

Ron Joseph