I've been building-designing furniture since about 1978. In the late 60s and early 70s was a professional bass player. In the early 90s I was at the super market and picked up a magazine showing an exploded view of a Fender guitar and it dawned on me " this is basically 2 flat pieces of wood with strings stretched across it" also the style was akin to a 50s surfboard! I thought to myself, I can do this! Well of course it wasn't that simple! After a first attempt at a 6 string electric guitar which at close to completion I threw it in the trash, I learned some with that experience and took some time contemplating my next project. I was a music major in college (briefly) and had some time on an upright bass. As I looked at the violin family of instruments, they have a artistic almost living anatomical look to them. Other than the Hofner bass few of the electric modern instruments had that traditional flowing design! With this observation in mind I wanted to design an instrument with a feel for the Cremona-Stradivari-Amati influence and I started building my first electric bass 4 string.
I had a nice chunk of curly Koa that was going to make a rifle stock and rather used that to build the instrument. It turned out pretty good and I play that bass now! After building 3 electric bass instruments with the violin look I set my sights on making the real thing! Over the next couple of years I started researching the history on the violin family with an emphasis on the upright Bass. The concept, evolution, construction, and materials used in the Old days were quite inspirational with the amazing fact of no power tools! I had to first build the mold with which dictate the exact form of the Bass. If one looks at what photos of the surviving older basses you find the amazing wide variation of size and shape! I found examples of many beautiful and many, forgive me, ugly ones! I found 2 Basses that looked to me to be the classic Italian form, One, a Carlo Guiseppe Testore,and Two, a Nicolo Amati. From the photos of both instruments I took a caliper and found the relative dimensional proportions (shape) and attempted to "morph" the two into one "offspring". this became the drawings and finally the mold that was used to build the first upright!
The finish (varnish) was the next challenge. I knew I didn't want to spray lacquer or modern finishes that I used on my furniture. I read quite a bit on the research and opinion (there is a lot) of the Cremona varnish(es). The conclusion I arrived at is that there is no exact specific agreed upon recipe that the Masters used! There is consensus on the general spirit varnish, oil varnish layers with the addition of Gum mastic and many other resins in the mix. After some experimentation I came up with an alcohol-shellac (spirit varnish) recipe with the addition of softer resins and heated. One can tweak the color by using the different grades of shellac flakes. I then use a top coat of a spar (oil) varnish that I further alter with hotter reducers Acetone-naphtha. The concept is to seal and color the white wood with spirit varnish first. I'm not a chemist but, it seems the very fast drying alcohol based finish seals the wood and dries with not much penetration and filing of the pores. The oil varnish then provides a protective topcoat to take what abuse may follow.
Sincerely,
Gerald VonTietz