A network for historic guitars and vihuelas
That is an interesting question. I always assumed it is a kind of French polish. Maybe our member Scot knows?
It has been answered on another forum. Commonly thought as being LampBlack (soot, plenty of it about during the 19 th century) in a varnish type medium - probably Shellac or Shellac with some other spirit soluble gum. It's unlikely to be an Oil based Varnish, although I suppose it can't entirely be ruled out. If it was Oil based the Black colour may have come from an earth pigment such as Asphaltum, which does readily dissolve in Oil. I've never tried Lampblack in an Oil Varnish.
As far as I'm aware no scientific analyses has been carried out on the finishes of Guitars from the 18th/19th century. It's highly unlikely that a strong opinion can be formed going by visual clues alone. If the Violin experts can't tell, then no one can. From a practical point of view it's more likely to be Spirit based. The trade Violins of the period are often thought as being Spirit varnish although the better quality types may have been Oil varnished. It's quite possible that they were using the two types side by side. That's what the Violin people tell me.
Charles Holtzappfel, in "Turning & Mechanical Manipulation". 1850, p. 1398 says: "Black Varnish. May be made with 3 lbs. of black sealing-wax and 1 lb. of shell lac to the gallon of spirit, or fine lamp black may be mixed with brown hard varnish or lacker, according to the thickness required in the varnish...." and goes on to talk about black matt varnish for the interior of telescopes, etc.
G.H. Hurst, in "Painters' Colours, Oils and Varnishes", 1892, p.450 in a list of various varnishes includes: 25. Black Varnish. - Asphaltum, 1 lb.; wax 1 oz.; lamp-black 3/4 oz.; and turps, 2 pints. And: 26. Common Black Varnish. - Coal-tar pitch, 1 lb.; coal-tar, 2 ozs.; boiled oil, 2 ozs.; and coal-tar naptha, 1 gallon. If not black enough, add sufficient lamp-black to bring the colour up."
The first of Holtzappfel recipes would be similar to a French polish, the other three would be considered spirit varnishes. Making them could be extremely dangerous if any heating was required.
For restoration work it would be worthwhile looking to furniture restoration suppliers. Various firms supply a black 'sealing wax' in varying degrees of hardness for filling dents and cracks in ebonised wood or ebony which might be useful, and our (fairly) local shop has always been friendly and sometimes helpful. A good artists' materials supplier should also help.
But what the makers actually were using, and if they were all the same, I don't know!
Peter. Is my memory correct in thinking that you did an article for the Strad on making Pine resin varnish? I guess it was in the early '90's.
Someone is responsible for the demise of my lungs and half of my street burning down! Neighbours weren't too pleased.
I'm afraid so! The 1988 article followed a talk AND demonstration (described as"a breath of fresh air"!) at the Violin Conference a year or two earlier, and I've been making and using only my own oil varnish ever since. So far no problems with neighbours.....
'88. That long ago. I have the article somewhere. On my first attempt I burnt the resin and the Oil caught fire. It turned out to have a lot of colour. Fastest drying oil varnish ever made! Subsequent attempts were much less exciting.
After going around in circles for a couple of hundred years it seems as though the Fiddle lot have finally concluded that the Strad varnish was just. . . Pine resin in Oil.
Hard to beat Oil Varnish on wood.
Yes. Pine resin with linseed or walnut oil. I'm now ageing fast and making less so may now have enough varnish to see me out! I find I've spent a day, sometimes two, making it about every five years. At current prices I've saved a lot of money! Stradivari was just good at using it.
Interesting... you apparently mean the "gentle heating" Holst is talking about on page 444 :-) (fortunately, both books available online: Holtzappfel, Hurst - thanks for the references!) Having a brief look on the other ones, glad the sandarac is locally available for me...
...so, how exactly did you prepare your own oil varnishes? Some improved recipes you may share?
How did you store them for 5 years?
Sandarac is a different type of resin.
These types of Oil varnishes can be very dangerous to make. The resin can give off acrid fumes and there is an exothermic reaction to be weary of. You can do yourself some serious damage if you don't take adequate precautions. Unless you have some laboratory type fume equipment it must be done outdoors. There is plenty of information over on the Maestronet Violin forum if you really do want to have a go at making your own. I no longer make my own. I had enough of trying to avoid the nasty fumes on windy days. These types of Oil varnishes are not like the typical modern Oil varnish that you can buy to varnish furniture or a boat. They last years. I have some that I made nearly 20 years ago and it can still be used.
If you don't wish to make your own you can try a Copal varnish from Lefranc & bourgeois. It's an old fashioned picture varnish but seems to work well for instruments. In theory it should be a little harder than your typical Pine resin varnish but that depends on the resin to Oil ratio. From what I can tell the Lefranc is 50% resin or at least they state 50% dry extract? Ideally you will need a UV drying cabinet but they are simple to make. Although my cabinet has 2 x 2ft tubes I only use 1 of the tubes to dry varnish. The same cabinet can also be used to tan wood. You also have to deal with dust issues. The enemy of applying these types of Oil varnish is dust. There are methods to help with this issue though.
It all sounds like a lot of trouble compared to Spirit or French Polishing but an Oil varnish can look very impressive - if you are prepared to apply it directly on wood.
I was originally frustrated by the difficulties of using a spirit varnish on a complex arrangement of surfaces like a cittern, and slower drying oil varnish seemed to have possibilities. Through FoMRHI I heard of William Fulton's use of oxidised turpentine, and related it to reading historical paint and varnish recipes at college several years before. So I tried them out, originally with sandarac, mastic and pine resins. My first results were written up in FoMRHI quarterly Oct 1979, and there are further comms. by Eph Segerman, George Stoppani and myself - all online. The first, pre-Dartington, Violin Conference was at Tiverton, Devon in May 1986 and was on Surface Preparation and Varnishing and I rewrote my talk for the Strad, April 1988. Nowadays I make three kinds - undercoat, colour coat(s) and top coat. We live at the end of a cul-de-sac and actually have 8 neighbouring properties, although the one next to my workshop is an open space, so varnish-making happens on cold, dampish days when the neighbours' windows are going to be closed. Dampish but not raining! An ideal space, which I had at Tiverton, would be a spacious and completely open car-port.
The danger of fire cannot be over-emphasised, and of interruption - children, dogs, accidents, just visitors.
I don't put my varnish directly onto the wood - it can look very pretty, but takes longer to dry, if it ever dries completely, and sinking in, seems to destroy the brightness of the upper notes for many years. Haven't kept up with violin circles where there has been a lot of discussion of the layer under the varnish. I use what I understand Gasparo used, which is dilute animal glue -glue size - also of course used to prime artist's canvas for centuries.