Sealers and grounds

[Anders Buen]

I would love to hear from anyone who uses already uses shellac, how you use it, and if you mix anything with it when you use it.

Thanks,

Craig T

I have been using shellac as a ground for many years, and pretty thick as strado mentioned. I use it as bought JOHA Spirituslack für Musikinstrumente - Grundlack. I think it basically is shellack, it does e.g. not polish as well.

[JimMurphy]

How does the chemical analysis of today's lac bug poop compare with lac bug poop of yore? And then there's molecular structure changes to consider as well.

Given dietary changes over time, there must be a "fudge factor" that'll need to be worked-out to match the optical qualities of Olde Cremona

lac bug poop.

Jim

[stradofear]

The main quality I haven't been able to match with shellac is that with a great Cremonese paint job, the microscopic structure of the wood sort of half disappears. Rather than being semi-transparent that you can sort of see through, down a couple of layers, the individual fibers and cells become so clear that you have a hard time seeing individuals. It's a lot like a thick stack of multible exposures, where each individual image becomes unrecognizable. That transparency is way beyond what shellac, alone, can do. It really does compare well to the holographic image on your credit card. Under a microscope, you can see in quite a ways without really being able to focus your eye on anything. With shellac looking really nice, I can see down three, four, maybe five cell layers, but the wood structure looks like it's made of lightly-ground glass, not clear.

This has a real effect when you're looking at a whole violin. If I can look at flecks and fibers, I know it's not there, no matter how clear you would call it.

[Janito]

That transparency is way beyond what shellac, alone, can do.

Has anyone tried rosin oil under shellac? If so, with what results?

[stradofear]

My concern about any semi-solid is that such things always dry, eventually, and then they become less good. Is rosin oil different? Lots of wet treatments look great while they're wet. Even turpentine looks great--for ten minutes. That's my concern about liquidish resins like Fulton's terpine, Canadian Balsam, venice turpentine, etc. Almond oil? What happens to it in the long run?

[Janito]

My concern about any semi-solid is that such things always dry, eventually, and then they become less good. Is rosin oil different? Lots of wet treatments look great while they're wet.

I agree.

There are accelerated testing methods devised that may answer the questions without a 100yr wait.

For example:

Testing parameters:

- 150C/ 20 min

- 90C/10days

- 65C/95%humidity/10days

- UV light/3 days

[stradofear]

Or, more directly, if you can cook it down to a solid resin, as you can with Venice turpentine, it's a no-go. Elemi is an example of a resin that's commonly in spirit varnish recipes as a softener; it's only good for that for as long as it's wet, which isn't forever. On the other hand, castor oil as a softener is, apparently, forever, or so the varnish chemist at a lacquer company once told me.

[Oded Kishony]

what's wrong with the resin eventually hardening?

[Janito]

Or, more directly, if you can cook it down to a solid resin,

The accelerated testing with an 'in use' form of the oil need not produce the same effect as cooking a 'concentrated' oil.

Molecular dispersion may affect the results (eg bonding between oil molecules versus not or bonding of oil and non-oil neighbours).

[Bassbow40]

Hi all,

I used, as ground, with very good results, rosin, in Italy we call it pece greca, it is the hard part that remain after turpentine distilling. After a esperiment I got it honey like consistency. I thinned with turpentine gum. You can see at http://www.maestronet.com/forum/index.php?...mp;#entry412330

[stradofear]

what's wrong with the resin eventually hardening?

When it hardens, the optical effect changes. The wood that looked so nice when it was "permanently" being wetted by a semi-liquid filler now looks different with something of a different RI saturating it. I guess if you only care about until it's sold. . . . ;-)

I had the reverse problem with some of my early violins. I despaired because the varnish was so opaque. Now, 20 years on in the oil drying cycle, they look great, and I wish I hadn't stripped so many. I have a little piece of wood with some varnish on it that I wish I'd written on it what I was trying, because the last time I looked at it, it was wonderful, and something I wouldn't mind waiting ten or 20 years to happen.

We run this danger with anything we use, but things which clearly continue to dry over long periods of time are the most unreliable.

[Michael_Molnar]

Strado,

Was this the article?

"Firm Ground" in The Strad, April 1989, pp. 275-278 by Barlow and Woodhouse.

[stradofear]

No, it was by a French woman who was in Ann Arbor for a while, who Jeffrey Holmes knows, and was specifically about shellac, only.

[Johnmasters]

I would love to hear from anyone who already uses shellac, how you use it, and if you mix anything with it when you use it.

Thanks,

Craig T

All of the woodworking magazines suggest a "spit coat" of shellac before finishing.

[actonern]

"All of the woodworking magazines suggest a "spit coat" of shellac before finishing."

Indeed, and the french polish method, using pumice as a filler, can quickly bring the wood's surface to a mirror shine with remarkable thinness...

To the extent mineral solids have been observed in past reseach as part of the ground, it is inviting to consider this as a potentially relevant factor in considering the use of shellac as ground.

Best regards,

E

[Johnmasters]

"All of the woodworking magazines suggest a "spit coat" of shellac before finishing."

Indeed, and the french polish method, using pumice as a filler, can quickly bring the wood's surface to a mirror shine with remarkable thinness...

To the extent mineral solids have been observed in past reseach as part of the ground, it is inviting to consider this as a potentially relevant factor in considering the use of shellac as ground.

Best regards,

E

I meant to say that it is such an old practice that there is a problem........ There must be lots of French violins that don't have this holographic appearance.

Stradofear, What do the best Vuillaumes look like?

[actonern]

John are you saying that French violins used French polish? I'm not aware that this is so or that shellac was used by French makers as a ground.

E

[Johnmasters]

John are you saying that French violins used French polish? I'm not aware that this is so or that shellac was used by French makers as a ground.

E

I thought that it was taken for granted that they used a spirit ground. Such as with gamboge and/or dragon's blood.

[Mike_Danielson]

Slow down lemmings, you are getting close to the cliff edge.

Now would be a good time to reread the literature review of Bruce Tai on Stradivari's Varnish and the most recent results of Echard et al. I think you will find there is no evidence of shellac used in the finish on Strads (except to fix corner bee-stings and as later french polishing).

Mike D

[tommyfiddler]

According to the paper:

Filippo Bonanni, Athanasius Kircher et les connaissances sur la gomme laque entre le XVIIe et le XVIIIe siècle / Claudio Canevari

(Bonanni,Athanasius Kircher and the knowledge about shellac between the XVII and XVIII century)

from the book:

De la peinture de chevalet à l'instrument de musique : vernis, liants et couleurs, actes du colloque des 6 et 7 mars 2007 / sous la dir. de Stéphane Vaiedelich et Jean-Philippe Echard

(From the artist paint to the musical instrument: varnish, binder and color...)

The usage of shellac as an ingredient of alcohol varnish seems obvious around the second half of the XVIth century when they where trying to reproduce Chinese lacquer or Indian varnishes.

In this document the same author says:

"Shellac is a material known in western world since 2500 years; in ancient times it was appreciated only

for the dying substances that contains, and as a drug of the ancient pharmacopoea. Shellac is the

secretion of the Tachardia Lacca, an insect that lives as a parasite on trees spread mostly in India and in

Indochina. From the 17th century it is used as a component of varnishes, alone or with gums and resins.

Starting with the revelation of Eustache Jamart to Athanasius Kircher of a secret recipe concerning a

varnish with shellac and alcohol, published by Kircher on Cina Ilustrata (Amsterdam, 1667), shellac

obtained in the following years a sudden diffusion all over Europe; an important witness is the Trattato

sopra la vernice detta comunemente cinese (Roma, 1720) by Filippo Bonanni. It is possible to find recipes of

shellac varnishes in bibliographic sources from the late 17th century; many of them are for musical

instruments. In the early 19th century one of the earliest quotations of the varnishing technique called

French Polishing is contained in an article from a French yearbook publication (Annales des arts et

manufactures : ou mémoires technologiques sur les découvertes modernes..., Paris, 1808). Lac dye has

become in present days a marginal product; nevertheless shellac is produced and refined in India in a

wide variety of sorts, following the crop periods and the host-trees for the Tachardia Lacca. Refining

techniques are either modern and semi-industrial or the traditional ones, similar to those used centuries

ago, described by the Europeans who visited India in the 16th century. Most of ancient shellac-based

varnishes for musical instruments are quite simple to reproduce, although after a precise choice of the

materials used."

my 2 cents...

-Tom.

[stradofear]

I meant to say that it is such an old practice that there is a problem........ There must be lots of French violins that don't have this holographic appearance.

Stradofear, What do the best Vuillaumes look like?

The very best Vuillaumes approach a middling Cremonese varnish, but usually they're less than that. Vuillaume, himself, said that he only did really well some of the time, and that he didn't know why that was the case.

I do not think that shellac or any other material I've used, or seen on any modern violin, is adequately holographic. The best moderns I've seen approach the better Vuillaumes, without getting even that far. If the Becker varnish looked on the back the way it looks on the top, and on the top the way it looks on the back, that would be very close, to my eye, maybe.

I think there are quite a few Mirecourt-type violins from around 1900 that are just shellac.

Mike, until someone comes up with something that really looks like, say, a nice Peter of Mantua varnish, or one of the other top-level varnishes, and as long as different researchers keep coming up with different lists of what's there, anything I read is automatically suspect. What lemmings do is rush from article to article, claiming "this is it!!!!"

[Johnmasters]

The very best Vuillaumes approach a middling Cremonese varnish, but usually they're less than that. Vuillaume, himself, said that he only did really well some of the time, and that he didn't know why that was the case.

I do not think that shellac or any other material I've used, or seen on any modern violin, is adequately holographic. The best moderns I've seen approach the better Vuillaumes, without getting even that far. If the Becker varnish looked on the back the way it looks on the top, and on the top the way it looks on the back, that would be very close, to my eye, maybe.

So send some spruce wood samples....

[Michael_Molnar]

FTIR analysis of the 1730 "Pawle" cello found two layers containing shellac and a proteinaceous material, while GC/MS revealed drying oil and pine resin.

A 1734 violin and the 1736 Paganini" cello also suggest shellac. Drying oil was also detected.

This is from Pollens op. cit. pp 263-4.

I don't think shellac can be ruled out.

Stay tuned.

Mike

[jmannsback]

Has scientific research proven that "shellac" constitutes any part of the baroque period Cremonese ground coats or varnishes? What about amber, dragons blood, copal - etc?

(edit) Then shellac must be an ingredient, according to the above.

[Oded Kishony]

It's quite clear (to me) that there is not one Strad varnish. It's look, texture and colors changed over the years. So a variety of ingredients are to be expected.

Oded