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Finishing Surface finishings have changed drastically in the present century. However regarding "antique" furniture we must think about three kinds of materials: Varnishes based in shellac. Varnishes based in copal resin. Wax. The first kind are finishings that are more or less based in a resin called shellac, product of the secretions of an hemipter insect called Coccus Laca, from the south of Asia, specially India. There are several kinds of shellac, mostly as a result of its processing. Presently the most common is the orange colored, sold in thin and little scales. It is dissolved in ethanol or methanol indistinctly. The most commonly used is methanol, but not necessarily the best procedure.. A rule of thumb in the preparation is to put a certain amount of shellac in a glass flask and then alcohol so as to cover it and "a little more". The solution must have a viscosity between water and milk to begin the process called "French polishing". This is a method of applying the shellac by means of a small piece of cotton wrapped in a thin, dust- free, non- fibrous cotton fabric. The solution is poured in a little amount at a time in the inside of the cotton and applied over the wood by means of a circular, non-stopping motion and a progressively more diluted solution, with the aggregate of little "touches" of pumice stone in powder as a filler of wood and vaseline as lubricant. The dilution and continuous rubbing has the effect of flattening the surface and giving, in the final steps when only alcohol is used, an incredible shine, impossible to obtain with other methods. Shellac has also reflecting and absolutely different tactile properties from other kinds of finishings. Shellac, at least when new, is identifiable without doubt:: something between oily-glass and silky. Conservation and restoration of this finishing presents many problems as shellac is extremely sensitive to water and alcohol (drinks and beverages). Therefore, valuable furniture with this kind of surface must not be used in daily living or similar situation. Being properly used, shellac finishing doesn't need special care, apart from being dusted and, in certain objects, carefully and conservatively rubbed with a microcristalline wax, and avoiding direct exposure to sun light. The restoration of shellac can be performed in two ways: its complete removal and remaking when deterioration is so extensive that seriously compromises the aesthetic carachteristics of the wood under it, or a careful cleaning and partial "remaking" of the finishing. The first process must be considered carefully taking into account the risk of destruction of deliberate staining or shading and\or natural darkening and other changes in the wood. It is strongly advised that this procedure (the complete removal) be made by an expert restorer and with methods that preserve the changes suffered by the object along its history (if they don't seriously compromise its aesthetic unity). Another important substance in finishings of antique furniture is hard resin varnish. As there are several kinds I will only mention the one that is made of copal resin, linseed oil and essence or oil of turpentine (or plainly turpentine). Copal is a hard resin obtained from different species of trees; linseed oil is extracted from the seeds of the flax plant, Linum usitatissimum and turpentine is a product of the steam distillation of oleoresins exuded from various conifers. The varnish prepared with these materials is hard, sparkling and with a little orange hue. When old, it becomes darker and pulverulent, due to its oxidation (oxigen absorption from the air). The restoration process in this case is different from shellac. Copal varnish can be removed partially with organic solvents, in order to thin it and make it more transparent. Then, it must be covered with a similar varnish, conservatively, or best with a synthetic and easily removable resin. Of course it can be removed completely with the same procedure but there are risks similar to shellac. Wax is mainly a combination of different natural and artificial waxes: beeswax, carnauba, microcristalline and others. For the purpose of this document I will only describe beeswax, which has been the traditional compound use in protecting wood and even finishings. Beeswax is a solid material with which the bees( Apis mellifica) build their beehive and is obtained as a subproduct of the processing of honey. The wax used for furniture and wood in general is a combination of beeswax and turpentine or synthetic organic solvents in a proportion so as to obtain a semisolid paste with which to rub wood after sanding (in plain wood) or carving. It is applied in small quantities and rubbed strongly to penetrate the wood, being left to dry and repeating the operation two or three times, depending on the absorption of wood. After this step, wood is rubbed again with a clean cotton or wool fabric to acquire a lustrous shine. Wax is not a good preserving agent due to its extreme sensitivity to water, humidity and greases, but gives wood a particular shine not obtained with other methods. In fact, there is a method in which two or three layers of shellac varnish are applied to wood and then it is waxed, acquiring a peculiar semi lustrous shine. Wax is easily removed -partially or totally- by means of a combination of water and ammonia and, less dangerous to wood beneath, organic solvents. Sometimes it is necessary to remove partially the layer of wax as in the case of varnishes. The progressive darkening of the finishing ,in the case of wax, is due to the absorption of dust and different kinds of materials present in the places it was kept, originating the "patina" which, in many cases gives the object the aesthetic appearence of the its age. Obviously, extreme care must be taken in the removal of the "patina" and must be done only if the extreme darkening affects the aesthetical appearence of the wood beneath.

1999 Darius Gubala