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I'm interested in your opinion on what's best for French polishing: pure shellac (with alcohol and the little bit of oil used in application) or shellac with resins or some other ingrediants. Is there a consensus on this?

Thanks,
Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

The best results are using flake shellac not canned.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Here is an old traditional French polishers' take on this question. It is easier to learn the French polish process and how they relate to each other using only shellac. Adding other resins can produce a harder film and a bit more moisture resistant. They also can take longer cure periods and make repairs al little more difficult if you don't know they are in there.

Really the only added resin I would ever consider using on French polish is Gum Sandarac.

Do not mean to divert the discussion but I do not want to start a whole thread for one little question.
Is methyl hydrate okay for dissolving shellac flakes? This is not for FP but just protective coat for rosette/ bindings.

P.S. thanks Michael P

I'm not sure what is meant by best.

There is a resin called B-72 that works very well as a hardener for shellac used in FP. There is a pretty good link here:

http://www.deller.com/newpage9.htm

There is also a magnificent document archived by the Gutenberg Project that goes through the formulas of a lot of historic finishes. I'll try to find the exact link and post it. A genuinely useful read, if only for the background.

Ah... here we go

http://www.gutenberg.org/ebooks/17935

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Jim Howell
Charlotte, NC

Yes. It is commonly used in places that don't have access to DA or pure grain alcohol. That said if you have acces to pure grain alcohol that would be my choice.

per B-72 MSDS it is a thermoplastic synthetic polyamer resin. its properties sound good and the artical was interesting but no thank you. I prefer natural resins for French polishing

Michael,

You are really making me stand up with much interest. I will soon start to FP a guitar for a friend with a very nasty sweat. He can really destroy a FP finish during just 1 summer time concert. I have read about sandarac before (perhaps even in one of your posts) and at that time I decided it is not really worth the trouble. But giving the fact that this person really has alien sweat from another planet, I guess any little bit of extra resistance is beneficial. What do you think? And how much sandarac do you suggest. I think I read max 1 to 10 parts of dry shellac before.

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Build log

With someone like this I don't recommend FP on thee neck. Tru-oil, Danish oil, nitro or CA are better neck finishes for aliens

Actually he doesn't seem to affect the neck, but the back where it touches the chest. And we both want FP Thanks.

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Build log

Well the Sandarac is a good option. not all do but IMO you need to heat the shellac and sandarac togather for an hour at 100F so that they almost become a varnish or you can buy Behlens' violin varnish pre botteled which is shellac, mastic resin and sandarac resin ready to use.

We use [flake] Shellac + 4 other [natural] resins. IMO, its much easier to begin with and learn using just flake shellac & alcohol before venturing into the apothocary's world of spirit varnishes.

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tim...
http://www.mcknightguitars.com

Hmmm... I'm interested in adding B-72 resin to shellac. It costs about $30 a pound here. I wonder how its toxicity is because I usually fp without gloves.

Wear gloves! I use gloves FP'ing for a couple of reasons. Foremost, is that I usually use denatured alcohol and you just never know what it was denatured with and secondly, the gloves provide a little bit of protection between my right-hand fingernails and the finish. I also clip my nails pretty short prior to FP'ing.

Taking chances with chemistry isn't worth it and gloves are cheap insurance, IMHO.

BTW -- a pound of B-72 goes a long way.

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Jim Howell
Charlotte, NC