(Revised 7/27/2014 )
My own varnish ground ideas based on practical testing...
{By David Langsather (c( 2014 }
(page one of four)
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...I started this phase of practical acoustics research reading all I could about possible traditional Italian varnish ground formulas. I did extensive experiments coating wood samples with test mixtures and then sound analyzing them after curing.
...Eventually, a short article about sandpaper by a medical doctor (but violin enthusiast) in a violin society monthly magazine (from many years ago) got me interested in Dutch Rush. I got a supply from my nephew's home where it grew as a decorative plant. Much to my surprise, it not only acted as a fine natural sandpaper, but had a profound positive acoustical effect on the wood is was applied to.
...This then suggested an investigation of Propolis when I read about this product as used in ancient varnishes to keep acoustical flexibity in the varnish layers for long periods of time. I purchased a supply from a bee keeper in on the internet. On receiving it, I decided to break it up into small chunks and store in in a jar covered with pure (real) 190 proof alcohol. Over several months, a dark red/brown color rose out of the propolis into the clear alcohol. When the alcohol became dark I brushed onto a wood sample and it too added positive acoustical properties.
...Now how about a combination of the two positive natural ingredients? This naturally lead to five possible combinations and I made an experiment to see what results might be. To my ears there was a clear acoustical winner (which I then used on my Opus # 27 violin; apparently with great success).
...You can read about the details on the link pages to the left.