ce qui est bien avec la propolis, c'est que cela soigne la mauvaise toux
!
en faisant une ptite recherche rapide avec l'ami Google (en effet c'est un vernis ancien pour violon, utilisé au XVIeme siècle, la propolis a en effet un tas de propriétés bénéfiques: antibactérien, graisseux, colorant... )
PROPOLIS MIXED VARNISH
This is an Italian type varnish which, in spite of being a very soft varnish, dries well. After is has been left to dry for a few days it polishes very well. As the name suggests this varnish is parly made up of propolis and is particularly fine quality. Its natural color is an antique yellow. This varnish should be smoothed with rottenstone and polished after is has dried completely, at least 30 days.
"PROPOLIS SOAP – Used as a Ground for Violin Varnish
by William Fulton
To introduce the subject of the ground I use under violin varnish let me present the following background:
In 1989 I attended the Tiverton Violin Conference in England and heard a presentation by Claire Barlow. It concerned the results of an investigation she had conducted on the ground that was used by the classical makers. She revealed that the ground appeared to contain something she described as “rubble.” Claire was unable to identify what the material was, but she did say, with some certainty, what it was not. Then in 1993 I attended a joint meeting of the Violin Society of America and the Catgut Acoustical Society and heard a presentation by Andrew Dipper where he discussed a mineral ground that he and Geary Baese were investigating in an attempt to reconstruct what Claire Barlow had discovered. That is the background now for my ideas on this mysterious ground.
I believe this ground was based on propolis, a byproduct of the beekeeping industry.
Back in the days of the old master violin makers, 1550–1730, people who kept bees didn't have the hives we have today. They kept their bees in skeps, baskets woven of straw. Each year, in preparation for the honey run, the beekeeper would clean the hive by leaching it in lye, the result of leaching wood ashes with water. (Today we scrape the propolis from the hive.) The lye would digest the propolis making the hive ready for the bees. This digesting process created a liquid soap from the propolis. It is my belief that this liquid soap was the source of the mysterious ground the violin makers used as an undercoat. (It was also probably used by artists of the time to make a smooth, sealed surface for paintings). Someone, be it the violin maker, artist, or perhaps a person who was engaged in dying cloth (it gives a beautiful gold color), would add alum (other metal salts can be used) to the lye-propolis mixture, precipitating an aluminum propolis soap. The resulting very bright yellow material, when washed, would be a very fine slurry ready to use as a ground.
How did the violin makers use this propolis soap? Here are my thoughts. The violin makers would scrape the surfaces of the violin smooth with scrapers. (You don't have to worry about the small imperfections caused by the curl of the maple picking out or small imperfections such as tool marks, etc., because they will be filled.) Then the wet slurry would be rubbed into the wood leaving a coating of this bright yellow soap on the surface. It is allowed to thoroughly dry and then it is rubbed, with the hand, to a very smooth, almost silk-like, surface. The material will fill all tool marks, all imperfections, gaps in the purfling, but the grain of the wood will be completely hidden. Next, a coating of clear varnish is applied and, if the index of refraction of the varnish is correct, the wood grain suddenly appears and the propolis soap will disappear. When dry, if there are any imperfections in the surface they are repaired by rubbing with more propolis soap and sealing with more varnish. This is continued until the surface is acceptable. Then more varnish is applied, a color glaze, and the instrument is finished.
This bright yellow aluminum soap actually seals the surface of the wood. The varnish is absorbed by the material but the varnish does not penetrate into the wood. When it is applied to the scraped surface, the top appears like corduroy, but the material fills the grooves of the corduroy, and the surface becomes smooth. After varnishing the growth lines in the top are accentuated, look darker, due to varnish being absorbed by the propolis soap.
Originally, when the skeps were leached in the lye, some organic matter other than the propolis was digested, such as dead bees, beeswax, etc. This gives a greenish-yellow color to the aluminum precipitate. To get a bright yellow color the liquid soap was allowed to stand until the organic matter formed a scum on top which was subsequently removed (It actually rots to form the scum.). Then a bright yellow color is produced when the alum is added. Of course today we do it differently but the results are the same.
The reason I believe this to be the ground is because it is, first of all, a very bright yellow, the color seen under most old varnishes, and, second, it is a product that was readily available to the violin maker.
PROPOLIS SOAP TODAY
Instructions on making propolis ground follow:
Fill a one quart glass jar half full of raw propolis as scraped from the bee hive. Add enough acetone or denatured alcohol to the jar to cover the propolis at least one inch. Allow the jar to stand until the propolis resin has dissolved, approximately 2 weeks. Filter the solution into a glass drying pan and place in a warm location to allow the acetone or alcohol to evaporate. (Some residual solvent will not affect the process). Collect the propolis resin.
Place 100 grams of propolis resin in a jar and add 300 cc of water. Add 3 grams of potassium hydroxide and heat the mixture, below the boiling point, to dissolve the resin; then filter the liquid into a clean jar (There should be an excess of propolis resin meaning all of the potassium hydroxide has been exhausted by the reaction).
Make a solution of alum (aluminum potassium sulfate) and water. A 5% solution is about right. Add this solution to the propolis resin solution causing a bright yellow precipitate to form. The reaction is complete when, upon standing, the precipitate settles to the bottom and the liquid above is clear. Pour off the clear liquid, add water and shake. Allow the precipitate to settle, then pour off the liquid and add more water. Do this several times to get rid of excess alum. Pour most of the water from the precipitate and filter. Collect the wet yellow paste into a jar and cap. This is the yellow mud that will be used as a ground."
All Bulletin articles are copyrighted © 1997 by Southern California Association of Violin Makers
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