restoring old shellac interior wood trim

txslimJuly 27, 2008

We are in the process of restoring early 1900's home with beautiful fir trim thru out. The old shellac in most places have bubbled/alligatored. What is the best process for restoring this finish? Some places are "sticky" - any suggestions for this problem? We're not looking to strip to bare wood if not necessary.

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I would get old rags and wipe down the wood with denatured alcohol. Rub thoroughly and that will remove the alligatoring and old dirt/grime. Then get new shellac and paint away, right over the old. New shellac will melt right into the old so there won't be any problems with having to clean down to the wood or anything like that. This is a fairly easy fix.

Shellac is available in clear, amber and garnet. Make sure you sample with the correct color to get the finish you desire.

    Bookmark   July 28, 2008 at 2:00PM
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** What she said!**

With the added caveat that the rags you are using are likely to be cumbustible waste so treat them carefully. Dispose of them in a closed container filled with water. In between uses hang them outside on a closthes line to air out and never allow them to get piled up or discarded in a trash can or you risk a spontaneous combustion-started fire that might burn down your house!

One shop I read about has a rule that rags must be in your hand, in your apron pocket or submerged in water.

You may need to use steel wool, as well as rags, to cut through the build up. Same precautions apply with the steel wool.

Good ventilation when working closely with alcohol (or shellac) will avoid a nasty headache, too.

The good news is that what your proposing is one of the simplest, most satisfying, refinishing jobs there is.

Oh, and atmospheric humidity also plays a part in shellac drying, so hot, muggy, days may be better spent at the beach.


    Bookmark   July 28, 2008 at 6:28PM
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Molly, Thanks for mentioning steel wool - I had a memory lapse and should have mentioned it. Ditto to the ventilation/combustion issues, too.

    Bookmark   July 28, 2008 at 6:36PM
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Shellac/alcohol will not spontaneously combust. You are thinking of oil-soaked rags. Once the alky evaporates, the shellac on the rags is inert, and no polymerization is taking place.
I feel that stripping with alcohol, while possible, results in a very slow job. Every time the rag begins to dry, the removal stops, the rag begins to drag, and needs to be re-wetted. I prefer to move the stripping along at a faster clip, and use a stripper; I recommend Kutzit brand for shellac/lacquer/varnish. It dissolves and destroys the shellac- it will not re-dry or re-form on the wood's surface.It also removes more of the shellac than alcohol can. This is important if you wish to sand the surface before re-shellacking. The old shellac would cause the sandpaper to clog.
Finally, the"hotter" stripper will do a better job getting rid of old oil, waxes, and polishes that may also be present on the woodwork.

    Bookmark   July 28, 2008 at 9:17PM
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I'll do my usual appeal for not over-refinishing.

But then I actually love the look of nicely alligatored shellac. And I'm not alone.

Did you know shellac is made from a resin produced by insects? I think that's cool.

It's natural to want to smooth down the worst of the bubbling and alligatoring, and clean out the dirt that collects in the cracks and calls attention to them. This is why I favor the denatured alcohol. For the express reason that it doesn't strip off all the shellac, just takes off the surface crud.

I would have a quick wipe, let it dry, have a look. Don't douse the whole thing, softening all the shellac at once, which can leave you with a wrinkly, mucky surface.

Either way, experiment in an out-of-the-way spot until you get the hang of it.

Good luck!

    Bookmark   July 29, 2008 at 12:59PM
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Are you sure you're correct? I would be so happy to find you are right and I was wrong because I do a lot of work with grain alcohol (book restoration/conservation) and I have been taking a great deal of trouble with all those alcohol-soaked wiping cloths. Would the denatured alcohol used for stripping act differently than grain alcohol? I would be delighted to hear I can safely dispose of them in the trash!

I actually meant to come back here and re-comment because of something I thought of today. The OP didn't say so, but in my house I have shellac over varnish grain-painting (in turn over an oil-based paint foundation). In some places the top coat has darkened and alligatored so as to make it not very pretty, but I know what's underneath it and am leaving it, for now. So a suggestion to the OP, make sure you don't have grain painting underneath. You can remove the alligatored top layer but it is a much more delicate job than just cleaning plain shellac if you want to retain this special decorative feature.


    Bookmark   July 30, 2008 at 2:09AM
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Finishes that harden by polymerization like varnishes and oils can create enough heat to cause combustion.
Shellac hardens by simple solvent evaporation, and whiule the vapors and the surface are flammable when wet, once dried their is no problem.
The evaporatin actaully cool the surface, so no heat is generated.

Denatured alcohol is ethyl alcohol treated to make it unsuitable for drinking.
A very common method is to add methyl (wood) alcohol.
The tax for liquor is not collected on denatured alcohol.

If you have a rag or wipe soaked with alcohol just rinse it under running water and then squeeze out and throw it away.

Varnish or oil rags can simply be spread out on the ground until dry and then disposed of.
The old method of putting them in a metal container can result in them smoldering, and even starting to burn the next time the container is opened.
It is the close confinement that allows enough heat to build up as polymerization occurs.

    Bookmark   July 30, 2008 at 5:31PM
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