varnish over shellac

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?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 then whatever.
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.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sounds like great advice to me. Really good call on the Zinsser premix, too. Practical experience? ;^)
That's how I found out!
Robert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 far.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Robert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.