Rubio Mineral Ground, 80g jar

for violins/woon instruments

The search for the right finish occupies woodworkers for many reasons. Historical authenticity as well as beauty and function motivate the use of classical techniques. Longevity, optical qualities, sound and handling are a few of the criteria used when looking for the right ground and varnish for musical instruments, and many furniture makers are guided by the same considerations. In order to simplify your search for unique and often hard-to-find products and literature, and guide you through our catalog, we have compiled the following section. 

Mineral ground  For many years scientists have been examining the varnish layers on violins from the time of Stradivarius and Guarneri. It appears that there is a layer of mineral matter just below the actual varnish, which is close to a mixture of materials bound with potassium silicate that has been pioneered by David Rubio. The mixture consists of calcium lactate, alum, manganese sulphate, titanium dioxide, yellow iron oxide and mica, which corresponds roughly to the spectrum analysis of historical instruments.

Application The wood is ragged with a 50% solution of potassium silicate. While it is still wet, a thin layer of the mineral ground powder mixed with ordinary tap water (contains chlorine) is applied with a rag. More potassium silicate solution can be used on top of this layer. Once the slurry has dried, it produces a hard concretious coat, which obscures the wood grain, and can be sanded before applying varnish. Brushing on a base coat of e.g. rosin oil renders the ground transparent.

Effect The mineral ground reacts with potassium silicate to completely seal the wood. Subsequent varnish applications do not enter pores. There appears to be a significant hardening effect which influences the sound and durability of the instrument. David Rubio recommends treating the parts while they are on the mould, from all sides. The case is thus completely enclosed. In conversations with Dr. Kremer we established the possibility that wooden sculptures that have survived for many hundreds of years without paint application were treated in a similar way. Mr. Rubio has an excellent website with further information at www.rubioviolins.com.