The Optical Magic Lantern Journal (May 1892)

56 The Optical Magio Lantern Jouraal and Photographic Halargor. more or less blistered, especially about the top, whereas the brass-work which has been subjected to the same heat is scarcely tarnished. And as the lacquer on the brass-work and the polish on the wood are, or should be, practically the same— viz., shellac dissolved in spirit—it is reasonable to suppose that the wood has undergone some process which renders the polish more liable to perish. With the cheaper kinds of lanterns it is often the practice to first size the wood and then apply the polish with a brush instead of a rubber, which latter is only used to finish with. This effects a great saving of time and expense, and the work looks quite as well as good French polishing until it is subjected to heat. In order to get rid of the blisters, the whole of the brass-work should first be taken off the lantern, and, if they are not numerous or deep, rubbing them down with glasspaper will be effectual ; but if the old polish is much damaged, the whole of it had better be removed, especially if there are any bruises in the wood. There are several ways of doing this—by scraping with a steel scraper, and then rubbing with glass-paper ; but it is difficult to get into the corners and mouldings. Another way is by washing with methylated spirit, which is a very tiresome job, and never removes it effectively; or by washing with a strong solution of potash. This is dirty work, but the colour of the wood is much improved by it. ; If the mouldings are not elaborate it will be found best to use the scraper and glass-paper; and in order to get into intricate places, such as the moulding on-the base, pieces of wood about 2in. long, of suitable width and thickness, should be shaped concave or convex, on which to hold the glass-paper, so’as to fit and go into the shape of the mouldings. The internal angles can be treated with a little spirit, and brushed out with a stiff shoe-brush which should, of course, be clean. The potash process will take all the polish off; but as water must be used to remove the potash, this is liable to warp the wood unless it can be done very quickly.on.a warm day. The woodwork of a lantern should never:-be exposed to the direct rays of the sun, which will, probably, split and warp it. On the whole, it will be best to try the scraper and glass-paper first. A scraper is a piece of steel about four by three inches, the same thickness and temper as a hand-saw; in fact, broken saws are often cut into scrapers, but they can be purchased for sixpence. The difficulty isto keep it sharp ; very few workmen can make them cut properly. The edge is first filed perfectly straight and square, then rubbed smooth on a hone. A piece of hard smooth steel, such as a bradawl, is then pressed along the edge, and if it is held nearly square will have the effect of turning it up, thus forming a burr, which is really the cutting part. The scraper is then turned round and the other edge turned over in the same manner. This can only be done properly after a deal of practice. To use the scraper, it is held at an angle of about sixty, and drawn along the wood in the same direction asthe grain. With very hard wood it can be used in any direction. Some work ‘men hold this tool by placing the two thumbs close together on the side nearest to them, with the fingers in front ; others place it in the palm of one hand, and hold the top edge with the fingers of the other. . If the scraper is sharp, and held at the proper angle, it should take off the polish sr wood in long shavings, and not merely in dust. Glass-paper lasts much longer and cuts better if used over a piece of flat cork ; or failing that, a piece of wood covered with cloth will do as well. If the wood of the lantern is dented or bruised the sunken parts should be covered by a piece of wet cloth, and a hot iron applied; the steam generated will cause the bruised wood to swell to its former size again. A common poker will be found convenient for this purpose ; it can be made nearly red hot if the cloth is thick and well wetted. Having removed the polish, and raised the bruises, the wood can be darkened by applying bichromatic of potash, dissolved in water in the proportion of 1 to 20. grain of the wood, and make it rough; it must then be rubbed smooth with fine glass-paper, taking care not to rub the stain into patches. If the colour is not dark enough, try a little stronger solution of the bichromate, or stand the lantern in a good light. It isthe light that causes the wood thus treated to darken. When the wood is quite smooth it is ready for polishing. The materials for French polishing are linseed oil, French. polish, methylated spirit, cotton wool and some clean cotton rag, a camel’s-hair brush, and the clean shoe-brush previously mentioned. The work should first be oiled all over, and wiped dry. A small quantity of cotton wool is then saturated with polish, and enclosed in a piece of rag: this-forms the rubber, which is then passed over the whole work in regular circular movements, taking care not to squeeze out the polish too fast, and continue until the rubber is perfectly dry, when a little more polish is put on the wood, which must be removed from the rag for the purpose. As the polish is gradually deposited on the wood it will be found that the rubber is apt to drag or stick. To remedy The water will raise the