Varnish ' Ground ' layer effects...

Page one...

..When this section is fully developed, I imagine it will be very useful to makers of new instruments. ...The mysterious first layer that goes on the outside wood surface before the varnish proper is applied over it is called the ground layer and was used by violin makers in parts of Italy in the 1600's and up to the mid 1700's. After that it was superceeded by other less successful (although easier) techniques. ...At its best, this ground layer has a hardening effect on the surface of the wood and helps it transmit sound better. It also provides another important effect, which is to absorb unwanted higher frequency vibrations {either high overtones of the vibrating strings or possibly the noise the bow adds to the sound) leaving a more pleasing sound specturm to be transmitted out from the violin. ...The varnish ground is made up of three main ingredients: mineral components. glue (water based violin making glue){either hide, hare, or fish bladder} bee based wax (either bees wax or perhaps propolis) ...Now for a disclaimer: I am no expert on ground systems, but have been experimenting with and testing some ground mixtures for the past several years. Some have resulted in negative results, and some seem to be positive. I do, however, believe that the ground layer of the varnish CAN play an important role in creating a good violin sound. ...A comment by Mr. Saconni in his book on Stradivair's violin making caught my attention when he said that the varnish of a Strad violin can be completely worn away without affecting the tone but if the ground layer is removed, " the tone is ruined!" So the ground layer can indeed play an important role in tone production. I imagine that over time, and after many trials, we will come up with usable and helpful formulations. ...I will tell you about some of the more successful ones I have tried so far and the results (so far as I can determine).

...To test acoustical properties, I cut a series of wood strips of instrument-making spruce and maple, sanded them to the same thickness of 0.100" (2 1/2mm; the same thickness as much of the violin plate) [quarter sawn]. The strips are supported at 22.4% in from each end and tapped in the middle with the eraser end of a wooden pencil. The microphone picks up the sound and is analyzed by a Hewlet-Packard acoustical analyzer. Screen results appear below:

... This first test is of maple wood sample # 02, (0.100" thick; coated with one coat of my (ground #CA) on one side only.). It was then exposed to Ultra Violet Light and re-tested after varying U.V. light exposure times. You can see how the sound spectrum is refined so that by the end of eight days both high and low frequency 'noise' is greatly reduced, leaving a wide-band pure tone to make music with. Sound vibration over 4,600 HZ is greatly reduced ( a good feature).

Maple strip; pre-treatment (5x amplitude on screen) (0 - 2,500 HZ frequency scale)

After 3-component ground and 24 hours of U.V. light exposure. (0 - 2,500 HZ horizontal scale)

After 36 hours U.V. exposure. (0 - 10,000 HZ horizontal scale)

After 8 days exposure to U.V. light. Notice how the higher frequency sound (above 5,000HZ) is filtered out while the base tone is broad and strong. (0 - 10,000 HZ horizontal scale)

...2,500 HZ range (full screen) pre-application of ground coating.

...After 24 hours of U.V. light exposure. (with a lower screen vertical amplification.) {2,500 HZ range}

...After 36 hours U.V. exposure, now with 0-10,000HZ horizontal scale range. {showing drop off of sound after 4,200 HZ)

...The same sample after eight days of U.V. light exposure; showing a sharp drop off of sound after 4,600 HZ.

...This next strip is Sample # 07, Spruce, treated with one coat of my ground # CA brushed on one side only:

...Post treatment with 24 Hours of Ultra Violet light exposure (and using a lower vertical scale amplification. (2,500 Hz horizontal scale).

Pre-Treatment,0- 2,500 Hz scale.

...Thirty Six hours U.V. treatment. 0-10,000 HZ horizontal scale.

...Final screen after eight days U.V. light 'development' 0-10,000 horizontal scale.

...Tap-tone change: 516HZ start; 528 Hz at 1 day; 568 HZ at 8 days.

...Sample # 19 Maple: ground # CA after: left, 36 hours right, 8 days 0-10,000 HZ horizontal scale.

...Tap-tone change: 280HZ start; 300 Hz at 1 day; 304 HZ at 8 days.

...This test of sample #33 ( spruce) using ground # DA (same as ground # CA with the addition of diamond powder (# 8,000 grit)

After 24 Hours (0-2,500 HZ)

After 36 hours (0-10,000 HZ)

...Notice that as time goes on with this #DA ground, the tone seems to develop both in amplitude (loudness) and range (larger area under curve for a bigger, fuller sound); notice also that the strong drop off at 2,080 HZ, at 36 hours has expanded considerably to about 5,000 HZ after 8 days.

Tap-tone change: 532 HZ start; 548 Hz at 1 day; 604 HZ at 8 days.

...Sample # 35 Maple, after 36 hours of U.V. light: Coated with ground # BA on one side.

...Sample # 41 coated with my ground # BA after 36 hours of U.V. light exposure. (0-10,000 HZ horizontal scale).