This is a polishing treatment which gives a very high and permanent finish to the polishing of superior woods. It is divided into five separate operations. Preparing the surface of the wood, staining the wood, oiling, filling the grain of the wood, and lastly, polishing. This last operation is in turn divided up into bodying-in, building-out and spiriting-out.
The first operation of preparing the surface must be carefully carried out ; what is level enough for ordinary staining and varnishing may not be satisfactory for French-polishing, as the high polish magnifies any rough patches and shows them up in very high relief. Scrapers are used for running over the surfaces of the wood, fine shavings are pared off here and there until the surfaces are dead level. The process is then completed by going over with No. 0 glass-paper. The edges particularly must be given meticulous attention that not so much as a splinter remains.
If the wood possesses a rich colour, no staining should be necessary ; but if a little stain would be preferable, there are three types available : (I) water stains are easier to apply than spirit, because they dry slowly and can therefore be laid on more evenly, and the spirit stain pitfall of overstating is unlikely. But they usually require several applications to obtain the required tone. Also, the wood becomes very wet, dries extremely slowly and consequently the grain swells, necessitating the services of the glass-paper to reduce to the dead level again. (ii) Oil stains are the best in many ways. They dry slowly and are therefore easily controlled, and the oil sinks well into the wood, giving it a mellow appearance. Two or three days’ wait, however, are necessary between staining and polishing.
Always remember that the wood must never be stained quite so dark as required, as the polish adds depth to the tone.
As soon as the stain has dried thoroughly, the surface of the wood should be oiled to throw the grain into prominence. This is done with raw linseed oil, applied evenly and lightly with a soft rag, free from fluff. Don’t put too much oil on, as it is liable to sweat through the subsequent polish, and crack it.
The grain must then be filled by rubbing over with suitably coloured plaster of Paris and spirit of turpentine, or by painting with a varnish prepared by mixing three ounces of orange shellac with half an ounce of powdered resin and half a pint of methylated spirit.
Any depressions not covered by the filler, must next be stopped with a ‘beaumontage’ made by melting beeswax with an equal quantity of resin.
The final stage—polishing, follows. This is a very ‘’ ticklish’’ process. The rubber must be carefully made by folding some cotton wool into an old handkerchief evenly—so that the rubbing surface is without creases. The polish is made by dissolving five ounces of best orange shellac in a pint of methylated spirit, to which is added a teaspoonful of gum arabic and gum copal. If the article to be polished is mahogany, an ounce of Bismarck brown should be added ; if walnut, a few drops of spirit varnish ; if ebony, some aniline black. For yellow woods, button shellac instead of orange shellac should be used, coloured to the right consistency by gamboge. Transparent polish is prepared by using ten ounces of bleached shellac to each pint of methylated spirit. All three processes of polishing—bodying-in, building-up and spiriting-out— must be done with a circular movement, and the rubber must never be left in one place. The bodying-up is the easiest, because the oil in the wood keeps it from sticking, but when it comes to the building-up, first the glass paper must be run lightly over the surface, and then the polishing proceeds— adding two or three tiny drops of linseed oil at a time to the rubber. The final stage of spiriting-out, is the process of adding extra lustre to the finished work. There are numerous important details, too intricate to be cited here, but the amateur French polisher is recommended to obtain French Polishing and Wood Surface Staining, published by Messrs. Foulsham, at one shilling net. (ii) Spirit stains dry very quickly, and in their case it is necessary to apply the way of the grain ; the brush should be run from end to end without removing; if it is lifted off and returned to the same place, a darker patch will appear where the halt was made. It is very easy to over-darken when using spirit stain, and great care should be exercised to avoid this. If it is overstained in any pait it should be painted with a little oxalic acid solution, and then sponged over with vinegar. If this last precaution is omitted, the French polish will crack within a vcar.