French polish
Encyclopedia
French polishing is a wood finishing
technique that results in a very high gloss surface, with a deep colour and chatoyancy
. French polishing consists of applying many thin coats of shellac
dissolved in alcohol using a rubbing pad lubricated with oil. The rubbing pad is made of absorbent cotton or wool cloth wadding
inside a square piece of fabric (usually soft cotton cloth) and is commonly referred to as a fad (also called a tampon or muñeca, Spanish for "rag doll").
"French polish" is a process, not a material. The main material is shellac, although there are several other shellac-based finishes, not all of which class as French polishing.
The finish is considered to be one of the most beautiful ways to finish highly figured wood, but it is also recognised to be fragile. It is softer than modern varnishes and lacquers and is particularly sensitive to spills of water or alcohol, which often produce white cloudy marks. However, it is also simpler to repair than a damaged varnish finish, as patch repairs to French polish may be easily blended into an existing finish.
, French polishing was commonly used on mahogany
and other expensive woods. It was considered the best finish for fine furniture and string instruments such as pianos, lutes and guitars. The process was very labour intensive, and many manufacturers abandoned the technique around 1930, preferring the cheaper and quicker techniques of spray finishing nitrocellulose lacquer
and abrasive buffing. In Britain, instead of abrasive buffing, a fad of "pullover" is used in much the same way as traditional French polishing. This slightly melts the sprayed surface and has the effect of filling the grain and burnishing at the same time to leave a "French polished" look.
Another reason shellac fell from favour is its tendency to melt under low heat; for example, hot cups can leave marks on it. However, French polish is far more forgiving than any other finish in the sense that, unlike lacquers, it can be easily repaired.
The pad is first used to put a thinned coat of shellac on, then thicker coats with small amounts of superfine pumice, a crushed volcanic glass. The pumice acts both as a fine abrasive and to fill the pores of open-grain woods. Each coat must be fully dry before the next application, to avoid lifting out the softened finish.
The 'fad' is commonly lubricated with an oil that is integrated into the overall finishArticle by Chris Baylor on describing the process of French finish including a mention of the use of extra virgin olive oil as a 'fad' lubricant.. This helps to prevent the 'fad' from lifting previously applied layers of shellac. Typically, "softer" oils, such as mineral oil, will produce a glossier and less durable finish whereas "harder" oils, such as walnut oil
and olive oil
, will produce a more durable finish.
Additives to the shellac mixture include sandarac (sap of an African cedar) and copal, sap of a South American tree. These and other additives combined with heat and light can make the finish tougher, by cross-linking the polymers and oils in the shellac.
The piece is usually finished off after leveling (1500 grit oil sanding), then light buffing with carnauba paste wax
. Too much heat or pressure from buffing will melt off the shellac and result in a bare spot that must be refinished.
Wood finishing
Wood finishing refers to the process of embellishing and/or protecting the surface of a wooden material. The process starts with surface preparation, either by sanding by hand , scraping, or planing. Imperfections or nail holes on the surface may be filled using wood putty or pores may be filled...
technique that results in a very high gloss surface, with a deep colour and chatoyancy
Chatoyancy
In gemology, chatoyancy , or chatoyance, is an optical reflectance effect seen in certain gemstones. Coined from the French "œil de chat," meaning "cat's eye," chatoyancy arises either from the fibrous structure of a material, as in tiger eye quartz, or from fibrous inclusions or cavities within...
. French polishing consists of applying many thin coats of shellac
Shellac
Shellac is a resin secreted by the female lac bug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes , which are dissolved in ethyl alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish...
dissolved in alcohol using a rubbing pad lubricated with oil. The rubbing pad is made of absorbent cotton or wool cloth wadding
Batting (material)
Batting is a layer of insulation used in quilting between a top layer of patchwork and a bottom layer of backing material. Batting is usually made of cotton, polyester, and/or wool....
inside a square piece of fabric (usually soft cotton cloth) and is commonly referred to as a fad (also called a tampon or muñeca, Spanish for "rag doll").
"French polish" is a process, not a material. The main material is shellac, although there are several other shellac-based finishes, not all of which class as French polishing.
The finish is considered to be one of the most beautiful ways to finish highly figured wood, but it is also recognised to be fragile. It is softer than modern varnishes and lacquers and is particularly sensitive to spills of water or alcohol, which often produce white cloudy marks. However, it is also simpler to repair than a damaged varnish finish, as patch repairs to French polish may be easily blended into an existing finish.
History
French polishing became prominent in the 18th century. In the Victorian eraVictorian era
The Victorian era of British history was the period of Queen Victoria's reign from 20 June 1837 until her death on 22 January 1901. It was a long period of peace, prosperity, refined sensibilities and national self-confidence...
, French polishing was commonly used on mahogany
Mahogany
The name mahogany is used when referring to numerous varieties of dark-colored hardwood. It is a native American word originally used for the wood of the species Swietenia mahagoni, known as West Indian or Cuban mahogany....
and other expensive woods. It was considered the best finish for fine furniture and string instruments such as pianos, lutes and guitars. The process was very labour intensive, and many manufacturers abandoned the technique around 1930, preferring the cheaper and quicker techniques of spray finishing nitrocellulose lacquer
Lacquer
In a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...
and abrasive buffing. In Britain, instead of abrasive buffing, a fad of "pullover" is used in much the same way as traditional French polishing. This slightly melts the sprayed surface and has the effect of filling the grain and burnishing at the same time to leave a "French polished" look.
Another reason shellac fell from favour is its tendency to melt under low heat; for example, hot cups can leave marks on it. However, French polish is far more forgiving than any other finish in the sense that, unlike lacquers, it can be easily repaired.
Process
The process is lengthy and very repetitive. There are also many similar variations in schedule and technique. What is described here is one such schedule. The finish is obtained through a specific combination of different rubbing motions (generally circles and figure-eights), waiting for considerable time, building up layers of polish and then spiriting off any streaks left in the surface.The pad is first used to put a thinned coat of shellac on, then thicker coats with small amounts of superfine pumice, a crushed volcanic glass. The pumice acts both as a fine abrasive and to fill the pores of open-grain woods. Each coat must be fully dry before the next application, to avoid lifting out the softened finish.
The 'fad' is commonly lubricated with an oil that is integrated into the overall finishArticle by Chris Baylor on describing the process of French finish including a mention of the use of extra virgin olive oil as a 'fad' lubricant.. This helps to prevent the 'fad' from lifting previously applied layers of shellac. Typically, "softer" oils, such as mineral oil, will produce a glossier and less durable finish whereas "harder" oils, such as walnut oil
Walnut oil
Walnut oil is oil extracted from English walnuts . It is about 50% linoleic acid, an essential omega-6 fatty acid. Walnut oil is also a good source of omega-3 fatty acids which are also essential to human nutrition....
and olive oil
Olive oil
Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...
, will produce a more durable finish.
Additives to the shellac mixture include sandarac (sap of an African cedar) and copal, sap of a South American tree. These and other additives combined with heat and light can make the finish tougher, by cross-linking the polymers and oils in the shellac.
The piece is usually finished off after leveling (1500 grit oil sanding), then light buffing with carnauba paste wax
Carnauba wax
Carnauba , also called Brazil wax and palm wax, is a wax of the leaves of the palm Copernicia prunifera, a plant native to and grown only in the northeastern Brazilian states of Piauí, Ceará, and Rio Grande do Norte. It is known as "queen of waxes" and usually comes in the form of hard yellow-brown...
. Too much heat or pressure from buffing will melt off the shellac and result in a bare spot that must be refinished.
External links
- Shellac Polish Application by Smith & Rodger
- French polishing in lutherie
- French polishing tutorial for guitars
- French Polishing and Enamelling, by Richard Bitmead, 1910, from Project GutenbergProject GutenbergProject Gutenberg is a volunteer effort to digitize and archive cultural works, to "encourage the creation and distribution of eBooks". Founded in 1971 by Michael S. Hart, it is the oldest digital library. Most of the items in its collection are the full texts of public domain books...
- French polishing method, by M. Tutin, cabinetmaker
- Top 10 French Polishing tips Terry Waters French Polishing
- Top Polishing & Wood Care Tips, by M&S French Polisher