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In the fall last year, there was a discussion of 'is it French Polish. Shawn, I believe, stated that he added Sandrac, mastic and kensoin gums to aid finish time and make the finish harder.

What sucess have others had with the formulas given. Does it reduce finish time and is it harder.

Can these recipes be applied using Braun tech?

What is the downside to these additives?

I can't see how other than maybe adding more solids to the mix, there by building thickness a small bit faster, that adding any of the above could speed up the process. The solvent still has to flash off. Some additives may aid in the application technique as in help keep the muneca from wanting to stick as the load dissipates.

Most everyone here knows this of me. I believe that the best and most beautiful French polish finishes come from the traditional repeated hand application of shellac, Alcohol, a little walnut oil as a lubricant, proper technique and the liberal use of elbow grease JMO

Michael,thanks,
Just wondering if, in fact, the finish is harder with the gum additives with no downside.

Bob,

There are numereous additives that you can use, should you choose. More solids can increase the speed of the build, but on the other hand you also face sticking issues. Given the Brune 1 day method using regular shellac, I don't see speed as a factor.

Additives are not a simple matter of "add something and the film is harder". The word 'gum' is a key. Some of these gums are very soft, and will soften the film. Others are hard. Some will increase the flexibility of the film; other's will reduce it. Many will impart a wonderful odor to the guitars. Some will alter the color of the french polish.

Very roughly, benzoin smells wonderful, and will increase flexibility. It also allows the gloss to come up very quickly. Copal is very hard, and adds to the solids content of the polish. Some have argued that Copal without any flexing gum added will eventually lead to crazing. So, a typical combination would be Benzoin and Copal.

The Artist's Handbook contains a vast amount of information about these additives. However, it is written from the point of view of painting repair and preservation, which is rather different than our needs. So, he may look in askance at something we use, and vice versa.

Also note that if you surf around on the web you will find contradictory claims for the same additive. Don't trust what you google - trust the book I mentioned above.

In other words, you need to become a finish chemist if you want to be sure of the effect and longevity. I basically go straight these days, with just a hint of additives mostly for the odor. Trust me, you'll want to eat your guitar with this stuff on it.

if you want to find out about these gums and their effects rad up on violin varnish, as they are among those used in that area of endeavor.

of those who are the usually cited u.s.authorities on using french polish on guitars, i.e. brune and clark, i can't recall their mentioning the use of them.

Just to add to crazymanmichael's post, there are several spirit varnish recipes that call for different combinations of of shellac, resins and oil. One of the most popular violin varnishes is the "1704 Varnish", if you google you will find many references. Here are a couple of variations of it.

1704 violin varnish recipe

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Rian Gitar og Mandolin

i should have mentioned also that violin varnish is not traditionally used for creating a french polish. it is traditionally applied with a brush and polished with pumice in various grades.

I know it was posted here before, and I don't remember who originally posted it. Never the less it has become a good read. This ebook has become a good read on the subject: French Polishing and Enameling by Richard Bitmead. It even includes recipes, although some of the ingredients are a bit hard to find now.

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Joe Breault
Merrimack, NH
Perpetual novice

The recipe I use is from Geza Burghardt who originally trained as a violin family builder so that is where his approach to french polishing comes from. The advantage is a faster build with a finish that is harder. Other than that it does not change the method of applying french polish, just that the liquid is shellac plus additional solids instead of just shellac.

I was PM'ed and asked for my recipe. I typed a long message, and decided it was worth sharing.

But before I post it, let me share what the Brune's said about these additives when I took there class. Richard said "you could spend a lifetime trying different additives" and talked a bit about their different properties. But then he concluded by saying they just use blonde or dark dewaxed flakes, and it's worked for them for decades. None of this nonsense about additives, buttonlac, buying shellac that hasn't been dewaxed, etc. The only important thing is to buy good flakes, and to use pure alcohol, not denatured, to his mind.

Hey, if it's good enough to refinish a Torres, it's probably good enough for all of our guitars. Don't think for a second you need any of these things.

With that said, I like to play with the additives, but go light, because I don't want warranty issues 5-10 years down the road. I do especially like the effects on the luster from a bit of benzoin.


my PM follows:
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My standard recipe is 500ml Alcohol, 50g shellac, 5g of Benzoin, and 5g of copal. However, I typically modify that while keeping the ratios the same. I.e., if I decide I want sandarac, I may cut the copalto 2.5g, and add 2.5g of sandarac. And I don't do it quite as precisely as my numbers suggest. The resins come in little natural pellets, and they often have a lot of tree parts or whatever embedded in them. If they look very impure, I'll add more than the recipe suggests than if they are very pure.

If you want a real thinker, visit this page: http://www.deller.com/newpage9.htm

I've played with this recipe, but haven't come to any conclusions. The B72 makes for a very tough finish (for shellac), but it's hard to get into solution, and it often precipitates out on me after awhile. I don't suggest it for a first time out, or for a customer's guitar, until you get a track record for it.

Fleta was known to have added acrylics to his polish for awhile (B-72 is an acrylic), and he had a lot of problems with his finishes crazing after awhile. I haven't had that problem.

I do recommend going light on the resins. If you want, after you make the main solution, draw a little off and add some more, and do a test piece. But it's really the shellac that is going to give you the shine and strength, and you don't want to adultrate it too much.

Note I wrote with authority above, but I'm a rank amateur. Take what I wrote with a huge handful of salt.

Great info. Let's hear more!

I understand Brune's point about straight french polish just working but understand that the discussion of additives and different qualities of various shellacs has been discussed by luthiers for over 500 years.

You will find that violin family builders have dozens if not hundreds of books written over the centuries just on various recipes for oil and spirit varnishes. Some even tried to make the point that Strad's had a secret varnish recipe...

Even with straight shellac there are variations in the quality and color of shellac. Even when Brune states that they just buy blonde or dark dewaxed shellac, those are formulas for how raw lac taken from resin deposits scraped from trees were processed. I dont think that Torres called in an order to LMI or any other place and asked for blonde or dark shellac...Luthiers have always had to obtain materials from various sources and then prepare them to the point where they could be used for luthierie. Very little is known about the quality or source of the shellac that earlier luthiers such as Torres used.

Compared to violin family makers we have very little written description as to how guitars were finished other than our observations of instruments that have survived. In general most of the Spanish guitar builders did not share their "trade secrets" as to how they built or what materials they used.

Shellac unless it has been processed to take out the wax will have some degree of wax in it. Likewise the color of the shellac has to deal with the amount of processing to get the raw lac to the point where it is the color shellac we need for the finish we desire. Button Lac is just a term that was used to described the look of mostly unprocessed shellac...it is dark because it is less processed than a "blonde" or lighter shellac.

Adding resins to a finish, whether it is done by a manufacturer or by an individual is done to change the base properties of the finish to get the result intended.

I have long been a proponent of french polishing as a finishing technique and for many years used just shellac and alcohol but it was after seeing Geza's results at the GAL 2004 conference as part of the french polishing class that I adapted by approach to french polishing by using his recipe. French Polishing is a method of applying a finish, not a recipe. The recipe can be as simple as "blonde or dark dewaxed shellac" and alcohol or more complex as violin family builders recipes.

On my latest guitar (#2) I'm using a premixed hard shellac made by the ubeaut company. I believe it has melamine added as a hardener.

This is the second guitar I've FP'd, the first was as per milburn, this time I've substituted the shellac flakes but use the same technique. I gotta say the I love this hard stuff, I cut it 50/50 with ethanol, and it builds real fast, far superior in both ease of use and resulting finish to the dewaxed shellac I used last time. It's a bit too soon to tell if it's going to be harder than regular shellac apparently it hardens with time, but at this stage the ease of use alone has me convince that I'll never go back to mixing my own.

I have done several different rag-on finishes. Some were shellac based some were spirit varnish based and a couple lacquer based. I have a hard time seeing that if it is not shellac based, how it can be applied in a French polish application.

The reason I say that is because to French polish means to body (build thickness),spirit-off (level the film by melting the the shellac with a higher concentration of solvent and remove excess oil) and glaze (polish the outer film with a light cut of shellac). Not all forms of finish allow you to do the spirit-off or glaze because the solids are not easily melted without causing issues. That does not mean that they can not be applied in a ragging application, just that they can not be done in a French polish application.

There may be some additives that add hardness to the final film. I am not a chemist, but I would have some doubt as to the degree of their actual usefulness, and due to lack of experience with them worry about their affect on the process. As it is important that the film melt with the application of solvent and re-harden into an amalgamated film. It is the ability of shellac to do just this that allows the process to work.

It does not matter if you follow the Burne method or the more traditional method of application. The solids Must be meltable and re-meltable into a single contiguous film. This is the key for a material to be suitable for French polish application process.MichaelP38957.5213773148

I think you have hit on the key point of what french polishing is about...the beauty of a french polish is that it can be easily repaired without changing the character of the original finish. Modern catylized finishes such as lacquers look great but are very difficult to repair compared to french polish.

One of the keys to the recipe that Geza Burghardt uses to french polish is that he heats the shellac/alcohol mixture and any resin additives to a boil for 6-7 minutes and then strains that mixture through a coffee strainer 3 times with each step before then adding more resins and repeating the heating/boiling process again with each step. the result is still mostly shellac/alcohol based but it just tempered by the additional solids. Other than being a slightly thicker viscosity than normally used it is essentially a thicker cut than a 2 or 3 pound cut of shellac.

I have applied straight shellac/alcohol under and over Geza's mixture and because the amount of additional solids is small by percentage it only helped to build faster and still spirited off and glazed the same.

I have started using it after in the past doing nothing but traditional shellac/alcohol french polishing because I liked the results and as a builder of traditional classical guitars it is about as non-traditional as I have strayed.

Before playing with any additives to change overwise traditional french polishing I would be very careful to make sure that it melts into previous coats or it could be a real mess..

I've heard the Brune method mentioned often in FP discussions on the forum. Could someone familiar with it give a synopsis of this process?

-Mark

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Mark,
The Brune method is a way to F/P in a day. Robbie O'briens DVD on finishes shows exactly how to do it.