Seedlac

by Nicholas Von Robison

Originally published in Guild of American Luthiers Data Sheet #150, 1980 and Big Red Book of American Lutherie Volume One, 2000



Seedlac resin, when combined with alcohol, gives a magnificent spirit varnish suitable for spraying or French polishing with qualities far superior to its better known cousin shellac. It’s more transparent, faster drying, harder, and more resistant to scuffing and moisture. The latter quality is of particular value as sweaty hands can play havoc on a shellac-based finish on a musical instrument. With all this going for it, it is not well known or used by luthiers to a great extent. The primary reason is that the major paint and varnish manufacturers buy most of the crop for their own needs, leaving little for the small-scale importers.

About 60% of the resin is collected from an area between Calcutta and Central India with lesser amounts coming from Myanmar, Thailand, and Laos. There is a distinct difference in the resin color from different areas. The lac west of Calcutta is yellow or orange, east and south of Calcutta it is red, a pale red in Assam, and a dark red in Thailand. The resin comes from various indigenous trees, primarily kusam (Scheichera trijuga) which has the best color (pale yellow) and quality, but others such as pala (Wrightia tomentosa), ber (Berrya amomilla), and ghont (Bursera serrata). Two crops occur each year, summer and winter, and they revolve around the life cycle of a scale-like insect (Laccifer lacca) which infests the host trees. This small (about the size of an apple seed) red critter was cultivated as early as 80 A.D. for the purplish dye it contains. But not until 1580, in the records of Akbar the Great, do we find any mention of seedlac resin for varnish making.