Violin Q & A: Color of Potassium Silicate

by George Manno

Originally published in American Lutherie #9, 1987 and Big Red Book of American Lutherie Volume One, 2000

On my first three violins, I used a gamboge solution to seal the instruments before I varnished them. This left a warm yellowish ground for me to work with. On my latest instrument, I used potassium silicate, like Sacconi mentions in his book, The “Secrets” of Stradivari. The back and ribs turned a beautiful cinnamon brown, but the top has a tinge of green in it. What, if anything, can I do to avoid this in the future?

I experienced this green tinge once myself. Now before I mix my potassium silicate with water, I put a tea bag in warm water and let it sit for a few minutes. Then I remove the tea bag and combine the two liquids, mixing well and applying it to the instrument while the solution is still warm. Try this the next time.