Varnishing string instruments offers urgently needed protection to the sensitive wood. It is also essential for the visual appearance of the instrument. There is no second chance to make a first impression! Varnishing high-quality string instruments clearly is an art of its own.
Varnishing, however, is also of great importance for the sound of an instrument. The priming coat plays an important role here because the combination of priming and varnish creates a muting effect. The term muting is rarely or not at all used when talking about violin making even though, acoustically speaking, it is almost as or equally as important as vibration itself.
This is also a field in which people keep on searching for the “secret of Stradivari”. There has been a lot of progress in recent years. Sadly, many antique instruments don’t have their original varnish anymore or were painted over later on and therefore are no longer representative in regards to originality. Varnish for sure is one of the essential components when striving for good sound. But without an efficient basis – I am referring to the non-varnished instrument – even the best varnishing comes to nothing acoustically.
The types of varnish used for violin making are usually extracted from natural resins. There is a difference between oil-based varnish and varnish containing resins that were dissolved in alcohol or rather spirit. Both types differ substantially in the way they behave during application and often also in regards to appearance and character.
I prefer spirit varnish because I have found that it works very well for acoustics.