"Wood Density" Selection Page... Water Test
Modified Last:5/2021
Page WS_14
By David Langsather, webmaster: www.violinresearch.com
..Here is a suggested quick and accurate way to determine the specific gravity {density compared to water} of small wood samples:
..These are what we will be using...
Electronic Gram Scale
Water container full to the top of water.
..Set this on a platter to hold any run off.
..Procedure is as follows:
* Have a sample of the top and back wood on hand for the test.
* With the platter under the filled water container, weigh them together and record.
* Have the "filled to the top" water container on a perfectly level table, on a piece of paper towel .
* Have a piece of waxed paper to put under the flat plate you will cover the water container with as you push this flat plate flush to the top of the water container's top surface.
* Select the spruce wood sample; and weigh it dry.
..Place it carefully into the center of the water and cover it with the waxed paper and flat plate. Push the covering plate down smoothly until flush and immediately remove.
..Shake any loose water from the piece of wood back into the water container.
..Again weigh the sample piece of wood and record.
* Again weigh the water container and record its weight
:: The difference of weight of the water container is the weight of the displaced volume of the wood's volume.
:: specific gravity of wood sample is the weight of the wood sample divided by the water displaced's weight.
;; Do the same procedure for the wood sample for the back plate (maple wood).
We want to select woods that have a density ratio of: top wood to back wood, of about <0.64>.
**** This ratio may be very important for proper violin timbre in the completed instrument.