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 Post subject: Removing Varnish or schellac from cabinet
PostPosted: Jun Sat 10, 2017 5:02 am 
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Joined: Nov Mon 05, 2007 11:08 pm
Posts: 2314
Location: Calgary Alberta
I have an RCA model A33 and it has the original finish, which looks fairly good. I believe someone has tried to put a coat of something on top of the original finish, but I can't tell what it is . It is a thin coat of something
Is there a way to find out if it is shellac or varnish? If I can find out which it is then how can I remove it and leave the lacquer and maybe put another coat of lacquer over it?
The finish feels sort of rough when you run your hand over it and small brush marks can be seen.

This is my third radio of this model and I would rather leave the original finish on.
Any ideas from you guys will be helpful.
Dan in Calgary


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sat 10, 2017 6:39 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Haledon, NJ, usa
Yes there is an easy way to determine if it is shellac or lacquer.

Shellac is affected or dissolved with alcohol and lacquer is dissolved with lacquer thinner.

So test an area out of sight.
If you put some alcohol on a rag and rub the area, shellac will respond and get sticky.... and lacquer will not be affected at all.
Lacquer thinner will make lacquer sticky but it will do nothing on shellac.

If you determine that it is lacquer you can remove it easily with a 50/50 mix of Acetone and lacquer thinner. But you must douse the area fully.. slosh it on like water or else the surface will only get tacky. If you really slosh it on heavy, the old finish will wash away or rinse off easily. But use a lot of the mix and don't skimp.
The old finish will wash away with ease... no scraping required.

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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sat 10, 2017 3:43 pm 
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Joined: Nov Mon 05, 2007 11:08 pm
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Location: Calgary Alberta
Pbpix the information you gave me is helpful, but can you tell me if I can determine if the slopped on finish is
varnish?
Dan in Calgary.


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sat 10, 2017 4:53 pm 
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Joined: Mar Sun 11, 2007 6:55 am
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Location: Mission Viejo, southern California
If it is not Shellac, there is probably nothing to do but refinish it. That, or just sell it.

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many of my radios http://s269.photobucket.com/user/FSteph ... t=3&page=1


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sat 10, 2017 9:34 pm 
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Location: Haledon, NJ, usa
chaz wrote:
Pbpix the information you gave me is helpful, but can you tell me if I can determine if the slopped on finish is
varnish?
Dan in Calgary.

The 'slopped-on' finish can be tested the same way with either alcohol or lacquer thinner.

But maybe it's polyurethane? ...then you've got a bigger problem removing it. Perhaps the 50/50 mix will remove polyurethane. If not you'll need to sand or find a stripper for polly.

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To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sun 11, 2017 1:52 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Charleston, W.Va.
Hi chaz,
+1 to previous comments by Peter and FStephen regarding determining the existing finish. But beware, this cabinet has a photo finish which from your photographs appears to be in very good condition. If you intend to preserve it, complete stripping is out of the question, as it will destroy the photofinish which can never be recovered. It may be that you have no choice but to keep this "slopped-on" finish, carefully sand it as smooth as you can using wet/dry paper, then apply a new clearcoat on top of it. Possibly numerous coats, sanding in between, to make the end result as smooth as possible. The trick will be to determine exactly what type of clear topcoat to use, which will be compatible with whatever "slopped-on" finish that has been previously applied.

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Poston


Last edited by Poston Drake on Jun Sun 11, 2017 1:54 am, edited 1 time in total.

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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sun 11, 2017 1:54 am 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 3772
Location: Sunnyvale CA
Pbpix wrote:
chaz wrote:
Pbpix the information you gave me is helpful, but can you tell me if I can determine if the slopped on finish is
varnish?
Dan in Calgary.

The 'slopped-on' finish can be tested the same way with either alcohol or lacquer thinner.

But maybe it's polyurethane? ...then you've got a bigger problem removing it. Perhaps the 50/50 mix will remove polyurethane. If not you'll need to sand or find a stripper for polly.


The only chance that lacquer thinner has is if the polyurethane is applied over the original lacquer finish, probably. One of the good things about polyurethane and why it is almost universal in new-made functional furniture is that it's darn near bulletproof. That's also it's biggest flaw for refinishing antiques!

Brett


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sun 11, 2017 2:33 am 
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Joined: Nov Mon 05, 2007 11:08 pm
Posts: 2314
Location: Calgary Alberta
Poston: I have to tell you that this cabinet does not have a photo finish.
This is the third one of these radio that I am doing and the others did not have a photo finish.
Here are some photos of the other cabinets and if you look at the grain of the wood you will see that
they are very similar. The quality of the wood is very good with matched veneer on both sides.
I will do some testing on the cabinet in question and go from there .
I do appreciate all the input and comments.
Dan in calgary


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sun 11, 2017 2:57 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3912
Location: Charleston, W.Va.
chaz wrote:
Poston: I have to tell you that this cabinet does not have a photo finish.
This is the third one of these radio that I am doing and the others did not have a photo finish. Dan in calgary

chaz,
That is great news, and I stand corrected. Some RCA radios of this era (USA production) did have photofinish, and not having personal experience with your Canadian model, you can perhaps understand my mistake. In any case, that is indeed a beautiful cabinet and its underlying condition certainly looks very good.

So the issue now becomes: Will you need to do a total strip, or can you somehow remove or otherwise deal with the existing "slopped-on" finish? I suppose the only answer will be to experiment, as you plan to do. I have a similar issue with a Zenith 6-S-52 console which I am presently preparing to restore. Cabinet in excellent condition, solid wood & veneer with no photofinish, but a slopped-on finish with some type of oil-based dark varnish-stain with many brush marks and lots of dust embedded in it. It is a textbook example of how NOT to restore a radio cabinet! In my case I think I will have no choice but a total strip/refinish.

Let's hope yours is not polyurethane. Many people, including Peter ("Pbpix"), have done some very outstanding refinish work using polyurethane. But those of us who have ever had to strip a polyurethane finish, whether on a radio or some other piece of antique furniture, know what a nightmare it can be. Hence the reason I have personally never used polyurethane in refinishing any antique piece.

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Poston


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Sun 18, 2017 11:43 pm 
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Joined: Aug Fri 28, 2015 9:26 am
Posts: 658
Location: Fort Mohave Arizona 86426
I would second what Poston says. Don't know of any radio or antique radio whose finish was ever poly. From mid 1920s until tube radios quit being made the original finish was close to 100% laquer. I would say 100% but then you know how that goes somebody would come up with the exception. I bought an original 1927 furniture repair and finish book with a radio section and the radios were being done in laquer with wash coats of shellac and rubbed out to a duller finish. Not a shiny piano like finish. Of course after this book was published I am sure that a lot of radios had a shiny finish or even on high end possibly a piano finish but they still used laquer, toning laquer and filler. Even in 20s they were using wood filler. I would bet that in the later years a lot of them used the wash coats also. Sam


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Mon 19, 2017 12:30 am 
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Joined: Aug Fri 28, 2015 9:26 am
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Location: Fort Mohave Arizona 86426
Here is the recipe they used in that book for varnish removal. 40% benzole, 35% denatured alcohol, 25% acetone, with a 1/4 pound of melted parrafine wax per gallon. The melted wax is added to the benzole while still hot and then is added to the other ingredients and agitated thoroughly to make sure it is mixed with all ingredients properly. After the varnish has been removed you use a wash coat of shellac to seal before finish coats due to the added wax. They do mention making two batches with the second one no wax so you remove the varnish with the 1st batch and then use 2nd batch and don't have to use the wash coat. I think I would use the wash coat regardless.Hard telling why they used the wax in it but this is a 543 page book and they seem to know exactly what they were doing in all respects of wood repair and finishing. Sam


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Mon 19, 2017 12:39 am 
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Joined: Aug Fri 28, 2015 9:26 am
Posts: 658
Location: Fort Mohave Arizona 86426
After further reading the wax was added so the mixture wouldn't evaporate before doing its job. They say the if the mixture won't stay on for at least 3 minutes without evaporating the wax is not mixed in properly. This will also remove paint . They state that if you are going to finish with laquer to use laquer thinner when you are done to remove the wax and any benzole remaining. In that case you would not need the second batch. Learn something new everyday :lol:


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 Post subject: Re: Removing Varnish or schellac from cabinet
PostPosted: Jun Tue 20, 2017 1:00 am 
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Joined: Aug Fri 28, 2015 9:26 am
Posts: 658
Location: Fort Mohave Arizona 86426
Did a little research on Benzole and it's not used much anymore but it looks like you can use toluene which is commonly available basically that is what benzole was. Of course if you are going to make this mixture you would want to use protective equipment especially gloves and a breather and either a face guard or goggles.
I am tempted to make a batch for paint removal. It would be a very runny consistently rather than a goo like most paint removers and would be close to the same price but if it worked well It would probably go farther than the paint remover "goo" . Would work for varnish and I would say shellac also.


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