CrystaLac Products are all non-yellowing, but sometimes yellowing still occurs. Why does this happen?
This is not due to anything in our products, but it is most commonly caused by tannins in the wood.
Here is what tannins are. "Tannins are complex chemical substances derived from phenolic acids (sometimes called tannic acid). ... The word tannin comes from the old German word tanna meaning oak. It refers to the use of wood tannins derived from oak trees that were used to convert animal hides into leather. (United States Department of Services, n.d.)"
When you paint/coat the wood, this wets these tannins and brings them to the surface. That is why sometimes when you paint raw wood without priming you don’t see discoloration until you apply the topcoat.
You can prevent this from happening by properly prepping your piece with It's Knot Shellac sanding sealer. It has tannin blocker built in to prevent this.
You can also use several coats of Universal White or our Flip'N'Awesome paints, as they have a tannin blocker built into the formula as well. With certain wood you will need more coats then others to fully block the tannins, especially if painting something white.
Another thing to keep in mind is ANY solvent or oil based products WILL amber over time. So keep this in mind if using any other products under CrystaLac products.
You can purchase It's Knot Shellac sanding sealer and tannin blocker here:It's Knot Shellac – The CrystaLac Store
And our Universal White here: Universal White DIY Tintable Paint Base, Primer & Top Coat All In One. – The CrystaLac Store