Sunday, February 21, 2010

Why did my white paint turn yellow after applying a coat of polyurethane to it?

Because you used the wrong varnish. Polyurethane varnishes comes in two types, aliphatic and aromatic. Aliphatic varnishes do not yellow, whereas aromatic varnishes yellow significantly. Check the label, as it should have this information there.Why did my white paint turn yellow after applying a coat of polyurethane to it?
The yellow is the color of the polyurethane itself. Just because it is made from an aliphatic diisocyanate does not imply that it is perfectly clear, only that it will not turn more yellow with exposure to UV light. Most polyurethanes used in varnishes are usually amber in color.

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