All Replies on Top Coat over Zinsser Amber Shellac - antique grandfather clock

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View Kent's profile

Top Coat over Zinsser Amber Shellac - antique grandfather clock

by Kent
posted 11-24-2018 04:04 PM

5 replies so far

View bondogaposis's profile


5848 posts in 3209 days

#1 posted 11-24-2018 04:29 PM

Zinsser amber shellac is not de-waxed, you are going to have adhesion problems if you try to put anything over it.

-- Bondo Gaposis

View Fred Hargis's profile

Fred Hargis

6436 posts in 3351 days

#2 posted 11-24-2018 04:51 PM

The adhesion problems with shellac occur with anything that uses urethane/polyurethane resins and some waterbiorne finishes, the problem isn’t with the shellac…it’s the urethane. Putting them on top of something like shellac that hasn’t been dewaxed may cause problems, though that’s not absolute. So the mixed messages you see are because some have had success, but likely most have not. Like Bondo said, the Amber is not dewaxed. The Seal Coat is, however. If you want to apply varnish over the Amber shellac, you could use an alkyd resin varnish like Pratt and Lambert 38 or SW Fast Dry Oil Varnish. One other thing, some will tell you to top coat the Amber with some Seal Coat and go ahead with whatever you do. Well, that might work…but shellac will melt into itself, the new coat dissolves and mixes with the previous coats. So there is some risk in doing that as well. It’s another one of those things that some have had success with and others haven’t.

-- Our village hasn't lost it's idiot, he was elected to congress.

View OSU55's profile


2658 posts in 2847 days

#3 posted 11-24-2018 05:56 PM

The nonpoly varnishes are an option, and since its a clock that wont be handled lacquer is another option . Never tried the brushing lacquer but spraying it is easy. Another option is to continue with the shellac. You could french polish the shellac and it will fill the grain. It would need to be rubbed back in gloss with 0000 steel wool or equivalent. French polish takes time but so will any finish to eventually fill the grain.

You might try just adding a couple of coats of shellac and rubbing it back in gloss without fully filling the grain to see if that suits you. I have also had success with sanding a coat of shellac with ~600, let the shellac dust fill the grain, then recoating. Shellac burns in (remelts) the dust into a contiguous coat. Another possibility is to mix a little oil based dye with wax and fill the grain with wax – can be problematic in the long term.

View Kent's profile


45 posts in 4692 days

#4 posted 11-24-2018 08:42 PM

Thank you very much.

View Kent's profile


45 posts in 4692 days

#5 posted 11-24-2018 09:31 PM

I think I will go w another coat or two of shellac w 0000 between coats.

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