Questions: French Polish VS Olive Oil

by Gary Southwell and Koen Padding

Originally published in American Lutherie #97, 2009



Stuart Mewburn from London, England asks:

A recent request for an instrument finished with olive oil prompted me to do an experiment. I took two pieces of European spruce, the same size, oil finished one and French polished the other. I used virgin olive oil, applying one layer a day with a cloth and finished the next morning with Micro-mesh. Over fifteen days it built up a lustrous finish. Over the same time I applied thirty layers of French polish to the second piece of spruce. The oiled spruce (fifteen layers) weighed 2g more than the bare wood. The French polished spruce (thirty layers) weighed 1g more than the bare wood. If these figures are multiplied up to the size of the lower bout it means that the oiled top adds 33.2g to the weight of the working part of the top and the French polish adds 16.2g. When you consider that a bridge weighs about 19g–20g that’s a significant increase in weight for the strings to drive.

The experiment begs a couple of questions. Has anyone done similar tests for other guitar finishes? To what extent does the mass of the finish affect the tone of the instrument? And as an aside, how well will a finish like olive oil hold up?