“I need hardly say that curious connoisseurs and anxious luthiers have devoted much time and thought to the fascinating but elusive problem of varnish making.”
“British Violin Makers” (1920), by Rev. W. Meredith Morris (B.A.), second edition, page 27.
This subject is extensive.
It is usually accompanied with a lot of mysticism, secrecy, and protected “intellectual” property.
Given that almost all details in violin making are “out there”, varnishing is one thing that could differentiate luthiers altogether, as there will always be one “using special ingredients” sometimes “a secret recipe by Stradivari that was thought to be lost” or any myth ‘of the day’.
That’s what sells violins in the end. The story or narrative behind the violin maker. The special hidden knowledge he or she possess that makes that ultimate sound like it does.
We’ll try to answer this question (or at least scratch its surface): “does coating the inside or outside the ‘music box’ matter to the end sound quality?”. The old masters believed it certainly would.
One turning point in violin history was when the Italian master notably Stradivari, Guarneri, and Guadanini discovered how to perfect varnish by preventing them from soaking the wood. They included in the mix a very specific protein that closed the wood pores and prevented this. Sadly, as of 2023, this protein has not been properly identified.
Well, let’s delve a bit on varnishing violins.
Here are some books on the subject, organised by date of publication (not relevance) in ascending order:
- “The Manufacture of Varnishes and Kindred Industries” by Livache & McIntosh. Vol. 1&2 (1908)
- “Protective and Decorative Coatings” by Joesph Matiello, Vol. 1-5 (1942)
- “Violin Varnish” by Joesph Michelman (1946)
- “Violin Varnish And Coloration”, by Martins Zemitis (1981)
- “Classic Italian Violin Varnish” by Geary L Baese (1985)
- “Varnishes and Very Curious Secrets, Cremona, 1747” edited by Vincenzo Gheroldi (1999)
- “Lost secret of Flemish paintings, including De Mayerne manuscript” by Theodore Turquet De Mayerne and Donald Fels Jr. (2001)
- “Stradivari Varnish”, by Brandmair/Greiner (2010)
- “Violin Varnish” by Koen Padding (2015)
- “Il libro dell’arte” by Cennino Cennini (2015)
One could apply a layer of hide glue, however, it comes with a few caveats. Let’s be honest, hide glue is not the best material to work with: it stinks, it changes with humidity and temperature, and its handling requires a lot of preparation. This method has been used before, but I think one might find good alternatives producing equally good tones in wood.
As noted by Helen Michetschläger on The Strad (Feb/2016), the book “Violin Varnish” of Koen Padding has provided good terminology on the phases required: priming, sealing, grounding, painting and varnishing.
For instance, one could apply spirit based sealer primers to do the job.
A sealer would have the ability to prevent the wood from darkening before the varnish is applied.
The tradition of violin making is widely different from maker to maker: one would apply (list is for priming or sealing – I’m not sure which one is what at this point – sorry):
- hide glue
- juniper gum
- goldenrod
- pine resine
- casein
- albumine (vernice bianca or protein): egg whites
- horse aloe
- bee propolis
- mastic gum (greek mastic)
- boiled linseed oil
- shellac
- “pozzuolana” (a type of volcanic ash)
- doratura minerale (or donatura varnishing)
- used in the final three stages of Padding’s finishing system: doratura rosso, vernice liquida, and lacca rubia (is it the so called “Byzantine Finishing System”?)
- potassium silicate (waterglass) followed by “rosin oil” (some turpentine derivative), or silica
User steveg (Maestronet) would advise to use a “thin solution of juniper gum dissolved in spirits, and colored with gamboge, or dragons blood. I then use an oil varnish that has been colored using terpinated extracts”.
Given that his previous remarks were “the reason you have not received very many replies is that many luthiers today keep some things secret, including me”, he could be either lying or putting you off the wrong direction!
And honestly speaking, after reading this I thought it was a witch’s recipe for conjuring and controlling demons.
Types of varnish
Oil varnish: the basic component is the oil that is cooked with a resin. Edgar E. Russ has a very good discussion on how he prepares his varnish and which type he prefers. It requires cooking, and a long time to let particles rest, avoiding head space in containers (oxygen) that could influence the coating.
Spirit varnish: base ingredient is the alcohol mixed with a resin. It’s sufficient to shake it and then apply it, not requiring any cooking or waiting time, as oil varnishes do.
One of the simplest and least expensive type of varnish to apply is synthetic polyurethane. This is a ‘secret’ actually, part of the ‘folklore’ of violin making to keep it a very mysterious thing, almost magical, made by gods.
Number of coats
Well, now we are venturing almost in pure randomness chaos.
You could apply from 1 to N coats without worrying on being wrong.
I’m kidding: I have no idea how many coats is the right amount of coating at this point.
I have read one suggestion though: for priming, apply two coats to the spruce part and three coats to the maple parts. Put in a dry spot and wait at least 12 hours (time or use of ‘sun’ here is highly disputed).
On another The Strad article on advice in varnishing (“8 tips for perfecting your violin varnish”), it reads “Spirit
varnishes, which tend to dry quickly by evaporation, can’t be
relied on to flow out, so are best applied in numerous thin layers”.
Some basic recipes
Extracted from a The Strad article: “Cochineal varnish became the signature appearance for instruments made in the Stradivari workshop”.
Shellac is “scraped from the bark of the trees where the female lac bug, Kerria lacca (order Hemiptera, family Kerriidae, also known as Laccifer lacca), secretes it to form a tunnel-like tube as it traverses the branches of the tree”.
This insect is in the same superfamily as the insect from which cochineal is obtained. The insects suck the sap of the tree and excrete “sticklac” almost constantly.
A simple Cremona Recipe (is it really or just another myth?):
- Add Four parts of linseed oil, two parts pine resin, one part horse aloe. Boil these things until they turn golden colour and yield a varnish.
- This formula produces a transparent golden varnish that is very easy to prepare and has all the properties that we were looking for.
Useful advice
- Stay natural, make your own substances and don’t use off the self products.
- Read (a lot) before applying it to your instrument
- See Davide Sora’s YouTube video on varnishing
- Interesting comment on the video: “What you see in the video is the application of the third coat of “colorless” (without pigments) varnish. Linoxin contributes a lot to the beauty of this nice yellow shade, but of course the underlying wood is not white and has been tanned about a week in the UV box and by the application of the casein which, due to its basic pH, darkens the wood by further oxidation”.
Links
- Casein sealer application: YouTube video by Davide Sora
- Blog post on “My Home Made Violin” on “coating the inside with protein”
Epilogue
This is such a vast topic that I numbered it on the title, as I plan to revisit it over time.