2343. Tracing Paper
Mix together by a gentle heat, one ounce of Canada balsam, and a quarter of a pint of spirits of turpentine; with a soft brush spread it thinly over one side of good tissue paper. The composition dries quickly, is very transparent, and not greasy, and therefore, does not stain the paper to which it is applied.
Never Walk One Way and Look Another.
2344. Impressions from Coins
Melt a little isinglass glue with brandy, and pour it thinly over the medal, &c., so as to cover its whole surface; let it remain on for a day or two, till it has thoroughly dried and hardened, and then take it off, when it will be fine, clear, and hard, and will present a very elegant impression of the coin. It will also resist the effects of damp air, which occasions all other kinds of glue to soften and bend if not prepared in this way.
2345. Method of Hardening Objects in Plaster of Paris
Take two parts of stearine, two parts of Venetian soap, one part of pearlash, and twenty-four to thirty parts of a solution of caustic potash. The stearine and soap are cut into slices, mixed with the cold lye, and boiled for about half an hour, being constantly stirred. Whenever the mass rises, a little cold lye is added. The pearlash, previously moistened with a little rain water, is then added, and the whole boiled for a few minutes. The mass is then stirred until cold, when it is mixed with so much cold lye that it becomes perfectly liquid, and runs off the spoon without coagulating and contracting. Previously to using this composition, it should be kept for several days well covered. It may be preserved for years.
Before applying it to the objects, they should be well dusted, the stains scraped away, and then coated, by means of a thick brush, with the wash, as long as the plaster of Paris absorbs it, and left to dry. The coating is then dusted with leather, or a soft brush. If the surface has not become shining, the operation must be repeated.