I am building a drop down desk. At this stage I have applied a seal coat (1
lb cut) of shellac (not dewaxed). I was planning to use shellac on the
whole cabinet (walnut). Now I am thinking of using varnish (not
polyurethane), at least on the desk surface. Does anyone know if the wax in
the shellac will react poorly with varnish or not? Any other thoughts?
The wax may cause any finish from adhering in some areas. If this was
pre-mixed shellac, like Zinser, you should be OK. If you mixed it from
flakes you might have more of a problem. I think in any case a light
suff sanding and maybe a wipe down with Naptha should minimize any
effects. Your really best bet would be a coat of dewaxed shellac and
By the way, Varnish is a very broad term for almost anything that has
an oil a resin and a solvent. Polyurethane is among those items and
even shellac can be considered a varnish. Regardless, shellac as we
all know can go under just about anything.
Yeah, I used lots o' that Zinser blonde and orange with lots o' over
finishes before I realized nowhere on the can did it say dewaxed. It
took a bit of digging to figure out that it wasn't officiall dewaxed.
I always dropped to one pound at most when using it as an under coat
or color separator and just had is as a sealer coat so pretty thin
coverage. Since then I've been more careful but I have scuffed it,
wiped it and laid down poly and lacquer over it and no complaints so
About ten years or so ago I mixed up the cans when they were more
similar. And then when I noticed the difference, I had a monster
brain shut down and kept using their plain shellac as a primer. I
have no idea what I was thinking of.
I was finishing some bookcases, and I sprayed them all with the plain
stuff as I didn't know what else to do. Thankfully with a good scuff
sand and a clean rag with some lacquer thinner the finish adhered
well. I was sweating bullets, believe me.
Then I ran into a painter (not a finisher to me!) and I was laughing
about my brain fart and I noticed he didn't get it.
I tried to explain to him that the sanding sealer was shellac as well
as the regular stuff, but he would have none of it. He was sure I was
full of crap since he had been using the regular shellac cut in half
for a primer for years.
I never convinced him that the Z brand sanding sealer was shellac, and
he never believed anything about shellac having wax in it. Since he
had been using the regular "waxed" stuff for years he had his own line
of reasoning. He argued, "How would finish stick to a primer coat if
it had wax in it? And how could you second coat your own first coat
if you had wax coating going on top of another wax film?"
In his defense, he was a fair hand at finishing cabinets, and he
wouldn't lie about that. He would certainly blame the materials
before himself, absolving himself of any blame. But he told me he
never had one adhesion problem EVER when he used the Z brand stuff in
all the time he had been using it.
Well, it may fly in the face of conventional wisdom, but that was good
enough for me. He is the one that actually got me using Z shellac as
a barrier coat and primer as a result of those conversations. I am
not as bold as he was though, I still use the sanding sealer as my
choice of primer/sealer.
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