Ask the Expert Question-and-Answer Archive

by Ron Joseph

July, 2003

Yellowing of Nitrocellulose Lacquer

Q. I prepared a nitrocellolose lacquer (coconut resin+ 3/4NCwolf + uv tex OB ciba). When I applied on tinted white surface following problems occurred:

1) At room temperature a slight yellowing was observed.
2) In sunlight a very high yellow tendency was observed

A. My first question to you is, what is the tinted white surface, is it also a nitrocellulose lacquer, and does it have a UV inhibitor in it? You may be experiencing the yellowing from the base coat itself.

Although you have a UV inhibitor in the clear lacquer, the base coat may be the suspect of the yellowing. The clear lacquer will not prevent the base coat from yellowing even with the UV inhibitor. Nitrocellulose lacquers are notorious for yellowing, if at all possible you may want to consider using a cellulose acetate butyrate (CAB) acrylic blend. These types of lacquers have been used in the automotive paint industry for many, many years with minimal color change.