Conversion Varnish over Shellac?

Finishers describe their experiences using shellac coats under CV. February 27, 2013

Does anyone know if it is possible to apply CV over shellac?

Forum Responses
(Finishing Forum)
From contributor A:
Sure, anything's possible but I don't think it would be the best idea though. It would be better to use catalyzed vinyl instead.

From contributor M:
I spray CV over Zinsser white shellac primer all the time. I havenít encountered problems.

From the original questioner:
Contributor M: Is the white shellac primer the shellac dewaxed sealer?

From contributor M:
The white shellac primer is not the same thing as dewaxed shellac, which is clear. The white is primer for painting, but I usually just spray it as both a primer and color coat and then spray the CV over it as a clear coat. You can put CV over either the white or clear shellac.

From contributor S:
Personally I wouldn't do it unless you have to because that's what manufacturer's tech support people have told me. I have done it though when I suspected contamination in the wood. It seems to have worked fine, except once when I didn't sand with a coarse enough paper after the shellac and I had adhesion problems with the CV. Now I use nothing finer than 240. The CV sticks to the shellac. Honestly, I don't know the long term prospects though.

From contributor R:
If you do it and anything goes wrong good luck trying to get the manufacturer to warranty it. Why would you want to do it? I am sure there is a chemically compatible solution to whatever problem you're having that the manufacturer of the CV would be willing to guarantee.

From contributor N:
I use Zinzer's seal coat under CV often without ever having a problem. I find it adds a bit of life to some woods that have a lot of figure like ribbon mahogany, cherry, knotty alder, et. I also use it on the same type of woods under waterbornes for the same reason, and once again without ever having a problem.

From the original questioner:
The reason why I'm intended to use it is because the results you achieve highlight the grain with shellac. To me it is the best way to show the richness of your creation.

From contributor D:
This is something I have done many times for the very same reason. I would recommend sealing with Vinyl sealer to ensure proper adhesion between coats.

From contributor N:
I have never found it necessary to apply a sealer over seal coat. It may be necessary if you are using a non-dewaxed shellac though.