cmk8895
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« on: February 20, 2009, 12:56:09 PM » |
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Hello all.
I have recently purchased a cylinder desk in beautiful condition with the original finish in place. I do NOT want to refinish the piece.
However, I noticed something odd about the finish. Testing shows it is shellac. In inconspicuous areas it is beautifully alligatored. However, in the exposed areas it is... something else. Instead of being alligatored or bubbled it is more like "puddled." There are quite isolated little bumps all over the surface. It's almost as if the alligatoring went nuts and sucked up into little thick puddles with irregular rounded shapes that I would normally attribute to a wet surface.
What causes this sort of thing? Is it alligatoring going to the extreme? What causes the old shellac to constrict into puddles and how does it do this without being in a semi-liquid form. Alligatoring is drying and cracking, but this just doesn't look like that.
Any thoughts, info, etc?
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Rare Victorian
www.RareVictorian.com
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« Reply #1 on: February 20, 2009, 12:59:52 PM » |
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I have a chair that sustained heat/fire damage that demonstrated something like what you described. Photos might help someone provide more information.
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JohnRVR
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« Reply #2 on: February 20, 2009, 08:07:26 PM » |
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Dear Sir,
I am curious to know how you 'tested' and 'confirmed' the surface on your desk was "shellac?" I would be happy to look at whatever photos you wish to post and advise you. I can tell that, with 95% confidence, what is on your desk is NOT shellac. Shellac does not 'alligator' nor 'pool,' no matter how long it has been around or what conditions it has gone through. Most likely you have an oil based varnish, that has separated over time, and is reacting in different manners due to the inconsistent evaporation of the 'carrier,' over said time and the subsequent reaction to the elements. It is also possible that there are several layers of different finishes, that either did not bond well to begin with, or the surface was not preppped correctly, or chemical reaction over time, has caused the varigated results. Let me know if I can help. Respectfully, John Hutchinson, RVR
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cmk8895
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« Reply #3 on: February 20, 2009, 10:05:54 PM » |
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Once my batteries charge up I will post some photos to help out.
John, I did the "solvents test" to see what it was. I Started by putting a small amount of lacquer thinner on the surface, letting it sit for about 30 sec, dabbing it back off then feeling for tackiness. There was none. So then I did it with denatured alcohol and the finish became very tacky. A gentle wipe with a q-tip wiped it right away.
I was under the impression that denatured alcohol would only soften shellac, not lacquer or varnish. If I am under the wrong impression can you please provide other information?
Photos will be forthcoming. Look for them in the morning (batteries seem to take forever to charge!).
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cmk8895
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« Reply #4 on: February 21, 2009, 11:24:35 AM » |
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Okey dokey, here is a pretty good pic of the front of a drawer. The entire finished outer surface of the desk is the same.
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« Last Edit: February 21, 2009, 11:26:15 AM by cmk8895 »
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JohnRVR
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« Reply #5 on: February 21, 2009, 05:54:23 PM » |
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Hello, saw the photo.
To answer your question in regards to the alcohol/solvent, Yes it will soften some varnish/oil based finished, but alcohol will not remove an oil finish. Mineral spirits will also soften the oil and actually remove an oil based finish. I can't tell based on the photo the age of the desk. I can tell you based on the photo it is definitely an oil based varnish. That is the only type of finish that 'balls up' like that.
The reason I use such a broad definition of 'oil based and or varnish' is because it was not until the late 1800's early 1900's that there was any standardized formulas for various finishes. Previous to that point, including almost all Victorian furniture, each manufacturer or cabinet builder made their own finishes. Some where highly guarded trade secrets. 90% of these oil based finishes were a type of Danish or tong or linseed oil, with varying ratios. As well, the carrier was mostly mineral spirits/turpentine but different shops used different things and different ratios: including benzene, gasoline, kerosene, etc.
So over time, the 'carrier' of the oil has evaporated and left the oil/varnish, which over more time has retracted onto and adhered to itself, hence the 'bubbles/balls.' That is also what causes 'alligatoring.'
You can gently clean and revive the finish without damaging it. At home, wash the piece as best as you can, with Murphys' Oil soap, let dry. Then if desired a light coat of Butchers' wax. I am nervous about telling you a blend of spirits and oil that we use to revive old varnish finishes, because I would want to test it before making any recommendations.
I hope that was helpful, if you have any more questions, let me know. Happy to help, if I can.
John, RVR
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jacon4
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« Reply #6 on: February 22, 2009, 11:11:54 AM » |
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well, i say that whatever finish is on there is in need to repair/replacement. in my view the most important element in preserving a piece of old furniture is a good finish.
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JohnRVR
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« Reply #7 on: February 23, 2009, 02:04:16 PM » |
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Great answer! Spoken like true collector. So glad you don't subscribe to the "Antiques Rodad Show" mentality. What's the point of having an old, possibly non original and very aesthetically unappealing finish on a lovely form of furniture. If you desire we can give you an estimate or provide a recommendation depending on where you are located. Happy to help,
John, RVR
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Michadi Antiques
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« Reply #8 on: February 26, 2009, 07:14:39 PM » |
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I would agree with John Hutchinson on this as I have never seen shellac alone take on that particular appearance. I looks to me that you have an oil-based overcoat applied over the original shellac. What ever finish was placed on the outer surface is chemically incompatible with the base. A shellac base would account for the softening of the finish with alcohol. This will not occur when the piece is finished in an oil based product only. Actually about 99% of the Victorian furniture you will come across was originally finished in shellac. You may be able to remove the outer surface without disturbing the shellac base, but the odds are against it. Short of completely stripping the piece and starting from scratch, your best bet might be removing the outer layer(s) of finish and overcoating what remains of the shellac base with 1 or more coats of fresh dewaxed shellac. You will want to mix you own and avoid using the store bought stuff. There are several ways to apply shellac, but "padding" will by far give the best result. Shellac can be tricky to apply correctly if you have not done it before, due to speed at which it dries.
Michael
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JohnRVR
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« Reply #9 on: February 27, 2009, 03:40:51 PM » |
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To some extent, I stand corrected. Often times you will find shellac underneath old varnish on Victorian furniture, however, based on my experience as a Restorer this is less common than an original varnish. That being said, the era in question is pretty large, and there were an enormous amount of shops, all with their own practices, in regards to finish. And over the subsequent one hundred years, anything could have been put on top.
It is possible, and we have done it, to remove the top layers of dirt, wax, varnish/oil, to get down to 'original' finish. However, this is not something I recommend for the 'Happy Homeowner' or collector, part. if you have kids or animals around. It is quite a chemical adventure to take down one layer at a time. And even further, the reason another second, third, or even a fourth finish was applied, is because the "original" finish was probably compromised or greatly diminished. That being said, I would like to know the course you choose. And its results. Much respect to all participants on this site. Thanks John W.
John, RVR
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jacon4
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« Reply #10 on: February 28, 2009, 03:51:19 PM » |
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Shellac is wonderful stuff and, most cabinetmakers use it today as a first step in finishing as it makes a great sealer.
I am with RV on this one, only times i've seen a finish ball up like that was from heat damage, basically cooked.
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