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

Very interesting article

Until he added the synthetic polymer his formula was a pretty common violin makers spirit varnish and very similar to the formula that Geza Burghart uses for his french polish. The synthetics he has added sound good and should give good results but the thing I would question is the repairablity of the finish later on.

A tradition basic french polish finish (assume alcohol and shellac only for discussion sake) is one of the most repairable finishes as new coats of polish will meld with the old base coat and build to a point where the finish is restored with little trace of its previous state.

As soon as the introduction of synthetics is added, little is known as to how this will interact if additional "repair" coats are added to the surface....it may be just fine but there is little to go on since even he had not worked with the formulation long.

The only part of the article that made me cringe is that he is positioning himself as a conservator and the first tenet of a conservator is that any change you made to the original object must be reversible at any point. That is why most conservators will stick to a basic french polish or determine what if any resins were added to the original french polish so that any changes made in the conservation process can be reversed.

When I read the GAL articles that Jeffrey Elliot did describing the guitars he restored for Shel Urlick, he went to great pains to make sure that he followed a museum quality conservators approach to every thing that he did in restoring these guitars.

I do like the fact that the article discussed the various benefits of the various additives and there is still tons we can learn by adapting our approachs to finishing to improve the durability and function of the finishes we use with musical instruments, I would just separation new finish approach from conservation approachs to finishing.

Thought provoking link! I am currently experimenting with sandarac at 10% by weight (compared with shellac flakes) using Hock flakes and DNA with walnut oil as a lubricant. Multiple sources reference the B72 polymer as an additive resin-- here is a reference to its properties:

B72 Information

The B72 seems like it might be worthwhile to look into and its readily available in small quantities from companies like Talas.

_________________
Jim Howell
Charlotte, NC

Shawn, a cursory search on the Internet turns up dozens of references to B72 being used in the conservation of museum objects. It can be dissolved in numerous solvents and so would appear to be removable in the future. Google for it. Very interesting.

Thanks Rick... very interesting indeed.

I collect historic guitars (pre 20th century, not vintage electrics ) but have always had others do the restoration and conservation work. I was not familiar with B72 but having read up on it it sounds like it could be a good thing to experiment with.

The recipe I am using for french polish is from Geza Burghardt.

For 21 grams of lemon-orange shellac flakes and 150 milliliters of alcohol (grain alcohol), he adds 3 grams each of sandarac, mastic and bensoin gum resins. The mixture is brought to a boil and is boiled on a low boil for 7 minutes. It is then left to cool completely and reheated to a boil again for 7 minutes. The is then strained through a filter 3 times and put into an airtight container.

The application of the french polish is the same as a basic shellac/alcohol french polish but it builds much faster because of the additional solids.

Geza shared this recipe in a session he, Cyndi Burton and Greg Byers did at the GAL conference in 2004 and since then I have been using it as my french polish and really like it. I have always stayed away from any other kinds of additives because of concerns over repairability but new additives like B72 (and the others mentioned in the article) make alot of sense as long as they can be repair easily.

Thanks.

Shawn--

Thank you for sharing Geza's formula. A few more things to try!

_________________
Jim Howell
Charlotte, NC

Where do you guys get mastic and bensoin gum resins from?

Thanks,

Graham-
I've gotten good service (and prices) from:
Wood Fnishing Enterprises


BTW, the benzoin is commonly listed as gum benzoin. It does add a nice smell to your FP mixture as well. Benzoin may be familiar to (rock) climbers as we used it (in the 'olden days') to help adhere tape to fingers and hands- it's sticky stuff.

Cheers
John

[QUOTE=JohnAbercrombie] Graham-
I've gotten good service (and prices) from:
Wood Fnishing Enterprises


BTW, the benzoin is commonly listed as gum benzoin. It does add a nice smell to your FP mixture as well. Benzoin may be familiar to (rock) climbers as we used it (in the 'olden days') to help adhere tape to fingers and hands- it's sticky stuff.

Cheers
John[/QUOTE]


Thanks John.

[QUOTE=Shawn] The recipe I am using for french polish is from Geza Burghardt.

For 21 grams of lemon-orange shellac flakes and 150 milliliters of alcohol (grain alcohol), he adds 3 grams each of sandarac, mastic and bensoin gum resins. The mixture is brought to a boil and is boiled on a low boil for 7 minutes. It is then left to cool completely and reheated to a boil again for 7 minutes. The is then strained through a filter 3 times and put into an airtight container.
[/QUOTE]

Thanks for this interesting post, Shawn. I have a couple of questions about the recipe. I would think that boiling the mixture lead to evaporating lots of the alcohol - is this so? What does this boiling process do to the mixture?

Thanks again!
Viv

[QUOTE=Vivian] [QUOTE=Shawn] The recipe I am using for french polish is from Geza Burghardt.

For 21 grams of lemon-orange shellac flakes and 150 milliliters of alcohol (grain alcohol), he adds 3 grams each of sandarac, mastic and bensoin gum resins. The mixture is brought to a boil and is boiled on a low boil for 7 minutes. It is then left to cool completely and reheated to a boil again for 7 minutes. The is then strained through a filter 3 times and put into an airtight container.
[/QUOTE]

Thanks for this interesting post, Shawn. I have a couple of questions about the recipe. I would think that boiling the mixture lead to evaporating lots of the alcohol - is this so? What does this boiling process do to the mixture?

Thanks again!
Viv[/QUOTE]

I just read the Deller article and would like to amend my previous questions. I am unfamiliar with this technology and have access only to basic consumer-level heating and filtering apparatus(es?). It sounds as though Deller uses a sophisticated heating "closed system" to minimize the amount of water adsorbed and a high-tech filtering system. So, assuming one has only a Pyrex flask or beaker, a hotplate, and average everyday shellac filtering capabilities, how would boiling and filtering the solution affect the properties of the mixture?

Thanks for your time and for sharing your knowledge!
Viv

I think if you carefully monitored and controlled the heat in a crock pot, you'd be fine with something like this. Alcohol is hygroscopic and even lab grade will fairly quickly absorb 5% water from the atmosphere; there's no way you're going to keep that out of French polish.   But you don't want the steam or water vapor of a double boiler possibly adding even more water to your mix.

It is possible that in the boiling process, the evaporated alcohol is condensed and returned to the French polish mixture.   Otherwise I would think it would thicken rather rapidly as the alcohol boiled off. A pressure cooker type setup might allow heating up the mixture without allowing the alcohol to boil off, but it also sounds like a recipe for a bomb.

[QUOTE=Rick Turner]    But you don't want the steam or water vapor of a double boiler possibly adding even more water to your mix.
[/QUOTE]

I've made this recipe myself and also watched it made at Sergei deJonge's shop. A water bath is the way to do it- a pot of water on a hotplate with a jar of FP mix partly immersed (keep it off the bottom of the pot with spacers- marbles or small stones work well)will work, or water in a crockpot, I suppose.
Nothing hi-tech required- use a wide-mouth jar aka pickle jar for the FP mix and keep the fumes away from open flames. The FP mix (alcohol solvent) boils at a much lower temp than the water in the bath, so you will not get much steam from the water. You really want a very gentle boil for the FP.
Make up any lost volume with more alcohol.
The boiling seems to promote some sort of chemical change with the resins and shellac- it's not about reducing the volume.

BTW, you should be prepared to dilute the finished FP to a working solution (1/1??) with more alcohol if necessary.

Cheers
John

I forgot to mention- I think the filtering steps are mostly to get rid of the various bits of stone, insect parts and twigs that the various resins (and some shellacs) can contain. A coffee filter works for this, or you could probably get away with filtering through a clean cloth.

John

[QUOTE=JohnAbercrombie]
The boiling seems to promote some sort of chemical change with the resins and shellac
John[/QUOTE]

I've been wondering about this, too. If anybody knows more about this, please chime in. A description of what's happening at the chemical/molecular level would be interesting; even more useful as far as I'm concerned would be a description of what changes are observable in the working properties (does it build faster, polish easier, etc?) and/or the performance (is it harder or tougher, does it reach "final" hardness sooner [rather than taking months or years to really harden up, as shellac normally does], etc?) of the finish.

Thanks.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/