How To Identify and Cure Automotive Clearcoat Yellowing Defects

Tags: Clearcoat · Paint Defects

Be Sociable, Share! Clearcoat may discolor over many years there is another problem when the paint you apply is an off color or yellow in comparison to the rest of the vehicle.

You will be left with a mismatch job that looks tinted when compared to the adjacent panel and yellow in hue.

The reason that this happens is due to either contaminated or improperly mixed clearcoat or technician error.

If the problem is the mixture of the paint it could be due to contaminated products or the wrong hardener or activator.

If the problem is due to technician error it is normally due to a much thicker application of clear then required.

To prevent this problem in the future you should discard any chemicals that are found to be contaminated. Often it is best to get rid of the whole batch unless it is a large volume container then you should make up a test panel.

Always follow the manufacturers technical sheets and use the right hardener and activator when mixing your clearcoat. Never try to adjust for room temperatures by adding more activator or hardener then recommended.


If the problem is due to technician error you should review the proper suggestions in the manufacturer’s technical data sheets for the appropriate amount of clearcoat to apply after a base coat. Normally this is between two and four coats however some systems only require one full wet coat at a close range to the surface of the vehicle.

Curing Clearcoat Yellowing

The only method of curing a mismatched clearcoat is to wait until the paint has cured fully and then sand and refinish.

Trying to sand out color mismatches is pretty much impossible however you do not need to go all the way down to primer you only need to remove all of the clearcoat then apply a full color coat and reapply the clearcoat at the recommended thickness.



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