Restoration of old shellac

Swanicyouth

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Nov 10, 2019
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I’m sure we all have seen it. Old American wooden veneer clocks with “bumpy” dried shellac. On car paint, we usually call this dyeback or sometimes solvent pop. I think with shellac I’ve seen it referred to as “crazing”.

I’m wondering, other than stripping completely & refinishing, what is the best way to deal with it? This is assuming it’s not trashed & you are not going for 100% perfection - just a big improvement.
 

glenhead

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Clean it with mineral spirits to get the grunge off. The focus is to get it about as clean as you can - you don't want to embed grunge in the finish. Mineral spirits will cut just about everything without harming the shellac, removing paste wax and dirt and whatever else there is. That'll probably make a big difference in the appearance.

To re-float the existing shellac you have to use the solvent for shellac - alcohol. If you use a new can of doesn't-contain-any-froo-froo denatured alcohol there will be minimal other "stuff" in it. Some people spazz about water absorbing from the air into denatured alcohol. The alcohol will evaporate faster than it will absorb water, so no need to spazz. Denatured alcohol is sometimes sold as glass cleaner and fuel alcohol and all sorts of other blah-blah at the big box stores. It should contain nearly all ethanol and methanol (maybe propanol or butanol too - all "ols") with almost nothing else. An example is Jasco Denatured Alcohol. If you can't find it, ask someone who has worked at the store more than four or five years - they'll know what it's called now. Try it in an inconspicuous spot first so you get an idea of how the finish is going to respond. Dampen a cloth (I usually use a piece of an ancient all-cotton t-shirt or flannel shirt or sheet) with denatured alcohol and rub it on the surface. It will frequently cause the shellac to melt just enough to ease out the crazing. Sometimes it takes a bit of work, and sometimes it'll remove the shellac. That's why "inconspicuous" is important.

You can also get a can of ready-made shellac and use it as-is or cut it by about half with denatured alcohol. According to the MSDS sheet the Zinsser shellac available at the big-box home-improvement store is nothing but shellac and denatured alcohol, so that should work well. (I make my own shellac using flakes and alcohol.) Using shellac on shellac is *the best* way to restore a shellac finish (as opposed to replacing it) - the alcohol causes the new to blend with the old and makes it all one finish.

Hope this helps.

Glen
 

Swanicyouth

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Thanks for the detailed explanation. This is pretty much what I tried, but with the 70% isopropyl - which is what I had close. Didn’t seem to do much, took a little brown off after mineral spirits. I have denatured & homemade shellac from flakes - will try that on next one.

I figured the 70% would be enough to level the surface - but maybe I was wrong. Someone may have refinished the clock before & used something else, maybe lacquer. From what I recall, lacquer is slightly soluble in alcohol. But I tried a little lacquer thinner & that didn’t seem to do much either.

Next time I will start with denatured.Haven’t had much luck “fixing” old shellac. It just doesn’t seem soluble or just ever so slightly; but not enough to make a difference.
 

Bruce Alexander

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Swanicyouth

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Thanks I will share some photos now & when I’m done…I was able to get the old finish “off” & the veneer only needed 1 repair on the body. A few chips were missing, but not too bad.

The door was a problem. It’s wood - & then this white plaster stuff. The problem was finish was in poor condition on the door - it’s was different - like leopard spots or fake burl wood or something (decorative). And, maybe it got damp - because the plaster was lumpy.

I ended up carefully sanding it all down to no finish/stain (door). Door does not appear to be veneer - so it’s diff than clock case. After sanding I was left with with plaster (door sides) & raw wood (door face). I decided to use a dark brown oil stain to try to make everything match & re-guild the gold around the glass w/ Rub n Buff.

Took some time, but seemed to work well - door & case are now a rich brown & match pretty well. Once the stain is dry 100% I think I will top it with shellac. The painting on the bottom part of the glass seems in decent shape - but the glass is held in with putty - and I decided to tape it up while refinishing instead of removing it

This is what I’m starting with:

05709F50-9E79-4357-86CB-600C6EBE495C.jpeg 991F56EF-3C65-49C0-8082-0E8EECE16151.jpeg 96ED8C12-8096-4302-92FA-AE8DF4B994DE.jpeg 7ECDF2A3-D496-475B-9EF0-AD37827221DC.jpeg


If you can see some white spots on the door wood frame - that is the plaster stuff I am taking about poking through. It looks like someone may have tried to refinish it at 1 point - or maybe wiped it down with a solvent that gummed up the finish. Once I started sanding - the door started turning white - all the wood was encased in this plaster - when I was done sanding: door front was wood & sides and slants were plaster. Stain I used evened it all out fairly well.

The cardboard dial is “dirty” (likely oil) & is about as good as it is going to get. Is the consensus generally to replace it or leave it?
 

Swanicyouth

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And done… Movement didn’t really need any work, besides clean & oil. Only thing besides refinish the case I did was replace some janky nails in the hinges with screws.

You can see the case came out lighter than the door. Used the same stain - the case was veneer & door was wood & plaster. 2 coats of spray shellac on top of stain. Gold around glass is Rub n Buff

The movement was supposed to be held together with taper pins - but was held together with toothpicks (see pic below! Replaced those with taper pins & the taper pin for hands as well. Polished the brass also

Clock is from 1860s to 1880 best I can tell. It just wants to tick. Seems like it can go another 150 years of cared for.


77099F2B-6FB0-4E4F-B49C-C2870C70AAB2.jpeg 075C7BFD-2DFA-4601-8550-1E9FAE528CBE.jpeg 934B9E5E-2F33-4FCD-832C-BB41948342DC.jpeg 9498C211-D851-43AC-A6C6-9513A6333BA4.jpeg 3B1ABEC8-FDCE-40E3-90CB-06FED314770D.jpeg
 

tracerjack

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You must be very pleased to see it come out so well. The dial gives it a nice antique look. Glad you didn't replace it.
 

Bruce Alexander

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Thanks for taking the time to share your before and after photos. The worst of the dial/face staining isn't even visible behind the closed door. I agree with TJ, repainting it would have been a mistake.

Did you change your screen name or open a 2nd account?
 

Swanicyouth

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I changed my contact email & got locked out & a mod fixed it - it may have changed my user name - but it’s the same account as far as I know?
 

Swanicyouth

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I just turned 2 away lol. I have 2 to start & 1 in the process.
 

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