French Polishing
Shellac and Pumice
The art of French polishing is steeped in mystique and legend, often poorly understood and explained. Frank frequently hears salespeople refer to so-called 'secret recipes' and long-lost or hidden knowledge. At its core, the craft of French polishing is quite simple: shellac and pumice powder are used with a rubber pad to fill the grain of the timber. Pumice, a volcanic silica-based rock—essentially glass—is an ideal grain filler because it is translucent. Although the basic principles are straightforward, mastering the craft is challenging. It typically takes about ten years to become an expert polisher.
Shellac comes from India and Thailand. It is a natural resin secreted by the Kerria Lacca, or Lac bug. These insects live on and feed off host trees, excreting a waxy resin known in its raw form as stick lac. Stick lac can be dissolved in denatured alcohol and used for French polishing in its unprocessed state. However, it is often further refined to produce different shades, from blond and white shellac to darker tones like garnet and button shellac. Shellac naturally contains wax, which is sometimes removed during processing to create a harder finish.
Some of the raw materials include button, garnet, orange, blond, and white shellac. Shellac can be purchased either with its natural wax content or as de-waxed. The de-waxed variety is slightly harder.
A French polishing rubber is used to apply the polish. Alcohol and shellac are fed into the rubber, while the cotton wadding acts as a storage reservoir.
A combination of pressure, the abrasiveness of the pumice, and a binding agent (shellac) gradually fills the grain.
A Brazilian rosewood loo table has been refinished using the French polishing technique. It features a beautiful, full-bodied finish with depth and clarity.
French Polish
Although shellac-based French polishing is simple in principle, it is difficult to master in practice. It is time-consuming and requires a high level of skill. Shellac is a natural, non-toxic resin that has been widely used for centuries and is still recognized as the best finish for fine furniture.
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Natural and non toxic. It has excellent properties for conservation. It is stable over time, flexible, reversible and has very good adhesion to almost any surface.
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Modern lacquers, although quick and easy to apply do not stand up to the test of time. They have a life span of 20 to 50 years.
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Frank is often working on shellac finishes which are over 100 tears old and still in good condition.
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Shellac is flexable which makes it not as hard as modern finishes, however it flexibility is what make it so durable, versatile and very compatible with timber, (a natural material that moves).
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Shellac flakes are dissolved in pure denatured ethanol and can be softened, reworked, re-built and re-amalgamated at any stage of it's life.
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Although Shellac based French Polish is synonymous with high gloss a range of reflectiveness can be achieved depending on how it is used.
French polishing is best done in components where possible. The photo above shows a chair leg being polished while still on the wood lathe.
Black japanned finishes became popular throughout the 19th century. Frank is highly skilled at reproducing and conserving these types of finishes.
A beautiful 18th century French commode veneered with Brazilian Rosewood, Tulipwood and Mahogany was refinished with shellac based French polish.
Throughout the Victorian era, shellac-based French polish was the preferred finish due to its ability to create a high-gloss, mirror-like surface.
The inside of a mahogany Dutch bureau the old shellac has been cleaned and a French polishing rubber was used to re-build the old finish.