Many decorative panels on the market change color after being coated with clear varnish. For example, white oak and white maple turn yellow after varnishing, and it's said that the longer the time, the deeper the yellow color becomes.
When choosing decorative panels, wipe them with a damp cloth to see the effect, as this is closer to the effect after applying clear varnish. Over time, decorative panels will inevitably deepen in color and oxidize, and the color will inevitably turn yellow. Choosing the right clear varnish is crucial.
The reasons for discoloration are as follows:
(1) Ester solvents in the clear varnish react with iron containers when exposed to water, causing blackening.
(2) Turpentine easily produces reddish-brown pigments in iron drums.
(3) Gold and silver powders easily undergo acid corrosion with clear varnish, causing the paint to turn green, darken, and lose its luster.
(4) Discoloration due to precipitation after prolonged storage.
The preventive measures are:
(1) For shellac varnish, which is most prone to discoloration, use non-metallic containers for storage.
(2) Add gold and silver powders before using the clear varnish; do not add them too early and store them in the varnish.
(3) For paints that have discolored due to precipitation, if it is not a quality problem, they can still be used after thorough stirring.
