French polish

Last updated
French polishing a table Restauratorin-bei-der-Arbeit.JPG
French polishing a table

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 denatured alcohol using a rubbing pad lubricated with one of a variety of oils. The rubbing pad is made of absorbent cotton or wool cloth wadding inside of a piece of fabric (usually soft cotton cloth) and is commonly referred to as a fad, [1] also called a rubber, [2] tampon, [2] or muñeca (Spanish for 'rag doll'). [3]

Contents

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 French polish technique is an excellent method to accent exotic wood grain. The finish is softer than modern varnishes and lacquers, and is particularly sensitive to spills of water or alcohol, which may produce white cloudy marks, as does heat damage. On the other hand, French polish is simpler to repair, as opposed to other traditional and modern varnish finishes.

History

French polishing was developed as a finishing technique in the early 19th century. [4] [5] In the Victorian era, French polishing was commonly used on mahogany and other expensive timbers. It was considered the best finish for fine furniture and string instruments such as pianos 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 pad of pullover[ clarification needed ] 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.[ citation needed ]

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 of them. 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 fad is first used to place a thinned coat of shellac. Once fully dry, thicker coats follow 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. It becomes transparent when saturated with the shellac, providing the deep gleam that brings out the wood's grain. Pumice tends to be messy to work with though and many modern woodworkers simply use fine-grained sandpapers (>4000? grit) to smooth off the earliest layers of shellac. The resulting shellac powder fills in the wood pores at least as well as, and often better than, pumice. The subsequent shellac coats will liquefy and surround this dust, filling in and sealing the wood pores like pumice would.

The fad is often lubricated with an oil that then becomes integrated into the overall finish. [6] This helps to prevent the fad from lifting previously applied layers of shellac. Typically, softer/ thinner oils such as mineral oil will produce a glossier though less durable finish whereas harder/ more viscous oils such as walnut oil and olive oil will produce a more durable finish. Although boiled linseed oil is commonly used as a wood treatment, it is too viscous to use for French polishing [ citation needed ].

There are two main variations to French polishing with regard to the use of pumice/ abrasives. In the original 'French Method', [7] both shellac and abrasive are applied and worked together. In the 'British Method', [8] shellac and abrasive are worked alternately.

Additives to the shellac mixture may 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. [3]

Related Research Articles

<span class="mw-page-title-main">Shellac</span> Resin secreted by the female lac bug

Shellac is a resin secreted by the female lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. Shellac functions as a tough natural primer, sanding sealant, tannin-blocker, odour-blocker, stain, and high-gloss varnish. Shellac was once used in electrical applications as it possesses good insulation qualities and seals out moisture. Phonograph and 78 rpm gramophone records were made of shellac until they were replaced by vinyl long-playing records from 1948 onwards.

<span class="mw-page-title-main">Resin</span> Solid or highly viscous substance

In polymer chemistry and materials science, a resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses mainly on naturally occurring resins.

<span class="mw-page-title-main">Manicure</span> Cosmetic beauty treatment for hands and fingernails

A manicure is a mostly cosmetic beauty treatment for the fingernails and hands performed at home or in a nail salon. A manicure usually consists of filing and shaping the free edge of nails, pushing and clipping any nonliving tissue, treatments with various liquids, massage of the hand, and the application of fingernail polish. When the same is applied to the toenails and feet, the treatment is referred to as a pedicure. Together, the treatments may be known as a mani-pedi. Most nail polish can stay on nails for 2–3 days before another manicure is required for maintenance, if there is no damage done to it.

<span class="mw-page-title-main">Varnish</span> Transparent hard protective finish or film

Varnish is a clear transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmented as desired. It is sold commercially in various shades.

<span class="mw-page-title-main">Lacquer</span> Liquid or powder coating material which is applied thinly to objects to form a hard finish

Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity.

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.

<span class="mw-page-title-main">Sandpaper</span> Abrasive material used for smoothing softer materials

Sandpaper, also known as glasspaper or as coated abrasive, is a type of material that consists of sheets of paper or cloth with an abrasive substance glued to one face. In the modern manufacture of these products, sand and glass have been replaced by other abrasives such as aluminium oxide or silicon carbide. It is common to use the name of the abrasive when describing the paper, e.g. "aluminium oxide paper", or "silicon carbide paper".

<span class="mw-page-title-main">Wood stain</span> Type of paint used to colour wood

Wood stain is a type of paint used to colour wood comprising colourants dissolved and/or suspended in a vehicle or solvent. Pigments and/or dyes are largely used as colourants in most stains.

<span class="mw-page-title-main">Wood finishing</span> Process of refining or protecting a wooden surface

Wood finishing refers to the process of refining or protecting a wooden surface, especially in the production of furniture where typically it represents between 5 and 30% of manufacturing costs.

<span class="mw-page-title-main">Rotten stone</span> Powdered rock used for polishing

Rotten stone, sometimes spelled as rottenstone, also known as tripoli, is fine powdered porous rock used as a polishing abrasive for metalsmithing and in woodworking. It is usually weathered limestone mixed with diatomaceous, amorphous, or crystalline silica. It has similar applications to pumice, but it is generally sold as a finer powder and used for a more glossy polish after an initial treatment with coarser pumice powder. Tripoli particles are rounded rather than sharp, making it a milder abrasive.

<span class="mw-page-title-main">Knife making</span> Process of manufacturing a knife

Knife making is the process of manufacturing a knife by any one or a combination of processes: stock removal, forging to shape, welded lamination or investment cast. Typical metals used come from the carbon steel, tool, or stainless steel families. Primitive knives have been made from bronze, copper, brass, iron, obsidian, and flint.

Wood putty, also called plastic wood, is a substance used to fill imperfections, such as nail holes, in wood prior to finishing. It is often composed of wood dust combined with a binder that dries and a diluent (thinner), and, sometimes, pigment. Pore fillers used for large flat surfaces such as floors or table tops generally contain silica instead of or in addition to wood dust. Pores can also be filled using multiple coats of the final finish rather than a pore filler.

<span class="mw-page-title-main">Polishing (metalworking)</span> Abrasive process for creating smooth finished surfaces

Polishing and buffing are finishing processes for smoothing a workpiece's surface using an abrasive and a work wheel or a leather strop. Technically, polishing refers to processes that uses an abrasive that is glued to the work wheel, while buffing uses a loose abrasive applied to the work wheel. Polishing is a more aggressive process, while buffing is less harsh, which leads to a smoother, brighter finish. A common misconception is that a polished surface has a mirror-bright finish, however, most mirror-bright finishes are actually buffed.

<span class="mw-page-title-main">Wood flooring</span> Product manufactured from timber that is designed for use as flooring

Wood flooring is any product manufactured from timber that is designed for use as flooring, either structural or aesthetic. Wood is a common choice as a flooring material and can come in various styles, colors, cuts, and species. Bamboo flooring is often considered a form of wood flooring, although it is made from bamboo rather than timber.

<span class="mw-page-title-main">Danish oil</span> Wood finishing oil

Danish oil is a wood finishing oil, often made of tung oil or polymerized linseed oil. Because there is no defined formulation, its composition varies among manufacturers.

<span class="mw-page-title-main">Floor sanding</span>

Floor sanding is the process of removing the top surfaces of a wooden floor by sanding with abrasive materials.

A grain filler is a woodworking product that is used to achieve a smooth-textured wood finish by filling pores in the wood grain. It is used particularly on open grained woods such as oak, mahogany and walnut where building up multiple layers of standard wood finish is ineffective or impractical.

<span class="mw-page-title-main">Tung oil</span> Chemical compound

Tung oil or China wood oil is a drying oil obtained by pressing the seed from the nut of the tung tree. Tung oil hardens upon exposure to air, and the resulting coating is transparent and has a deep, almost wet look. Used mostly for finishing and protecting wood, after numerous coats, the finish can even look plastic-like. Related drying oils include linseed, safflower, poppy, and soybean oils. Raw tung oil tends to dry to a fine, wrinkled finish ; this property was used to make wrinkle finishes, usually by adding excess cobalt drier. To prevent wrinkling, the oil is heated to gas-proof it.

<span class="mw-page-title-main">Conservation and restoration of silver objects</span> Preservation of heritage collections

The conservation and restoration of silver objects is an activity dedicated to the preservation and protection of objects of historical and personal value made from silver. When applied to cultural heritage this activity is generally undertaken by a conservator-restorer.

<span class="mw-page-title-main">Lacquer painting</span>

Lacquer painting is a form of painting with lacquer which was practised in East Asia for decoration on lacquerware, and found its way to Europe and the Western World both via Persia and the Middle East and by direct contact with Continental Asia. The artistic form was revived and developed as a distinct genre of fine art painting by Vietnamese artists in the 1930s; the genre is known in Vietnamese as "sơn mài."

References

  1. Sam Allen (1994). Classic Finishing Techniques. New York: Sterling Publishing. p. 42. ISBN   0-8069-0513-1.
  2. 1 2 Allen , p. 30
  3. 1 2 "milburnguitars.com".
  4. St Leger Kelly, David (2006). "'French Polish' in the Nineteenth Century". Furniture History. 42: 153–178. Retrieved 26 June 2021.
  5. Bitmead, Richard (1910). French Polishing and Enamelling (4 ed.). London: Crosby Lockwood and Son. pp. Preface, 18 ff. Retrieved 26 June 2021.
  6. "How to French Polish Your Woodworking Project".
  7. Allen , pp. 36–41
  8. Allen , pp. 41–46