The results of research by a number of writers are summarized and additional research by the authors is presented. The acoustic function of the ground varnish is discussed. A case is made that the ground varnish should have the lowest possible penetration into the wood. Emulsion varnishes have lower penetration than solvent-based varnishes. It is proposed that the ground varnish layer widely used before 1750 consisted of an oil-resin mix, emulsified with glue and stabilized by the addition of clay particles. This was applied directly to the wood and acted as both sealer and ground. The method of making and applying such a varnish is described. The physical and chemical properties of this varnish are similar to those measured on classical instruments.
Harris, Nigel; Sheldon, Roger; Johnston, James D. (2007) A Recreation of the Particulate Ground Varnish Layer Used on Many Violins Made before 1750. In: Journal of the Violin Society of America, Vol. 21, No. 1, pp. 145-159. Available at https://openmusiclibrary.org/article/157324/.