Michael Dresdner

straight talk about wood finishing

Misguided advice?

Q: I am finishing some beech and used Zinsser SealCoat in a 50-50 mix with denatured alcohol. After light sanding I applied tung oil but the result was some serious blotching. I’m planning on using shellac as a finish.
A: Zinsser SealCoat is pure, dewaxed shellac, already reduced to exactly the right consistency. That implies two things. First, there is absolutely no reason to thin it when using it as a sealer coat. In fact, thinning it that much turns it from an almost perfect sealer into something almost completely useless. Second, all you need do for a shellac finish is continue to apply coats of SealCoat until you are happy with the results. It’s a very simple and very effective finish. I don’t know what possessed you to put tung oil on wood you want to finish in shellac – perhaps some misguided internet chatter – but as you now know, doing that was both pointless and problematic.