(1) Various substances have been proposed as fireproof coatings for the protection of woods employed for building purposes, but most of them have been abandoned as being either too costly or not sufficiently durable. The following, invented by Vilde and Scham-beck, seems to succeed. The paint consists of 20 lb. finely-pulverized glass, 20 lb. finely-pulverized porcelain, 20 lb. any sort of stone in powder, 10 lb. calcined lime, and 30 lb. water glass (silicate of soda), such as usually found in commerce. The solid elements, having been powdered as finely as possible and sifted, are moistened and then intimately mixed with the water glass. This yields a mass of syrupy consistence that may be employed for painting either alone or mixed with colour. The addition of the lime gives a certain unc-tuosity to the mass for whitewashing, and its combination with the silicic acid of the soluble glass serves to bind the other materials together. The proportions of the different elements above mentioned may be changed, save that of the water glass, which must remain constant. These elements may even be replaced one by another; but it is always well to preserve the lime. Instead of the silicate of soda (soluble glass of soda) soluble glass of potash might be used, but the former is less expensive.
The coating is applied with a brush, as other paints are, as uniformly as possible over the surface to be protected. The first coat hardens immediately, and a second one may be applied 6 hours or more afterwards; two are sufficient.
(2) Take of common lime, freshly slaked, of hydraulic lime, and of sili-cious or argillaceous matter (sand or pulverized slate), equal parts; to which add cows' milk in sufficient quantity to give the whole, when thoroughly mixed, the proper consistency for laying aud spreading with the ordinary brush. Any desired colouring matter may be added. The addition of glue or rosin may in some cases be of value. The proportions may vary considerably, but those above given are considered to produce the best result.
(3) Dissolve crushed rosin in turps sufficient to make it as thick; as cream. Then mix together in a paste oxide of zinc and boiled linseed oil, and add it to the other; it will become white. Thin it out for use with boiled oil and turps. The above paint will take most pigments, and should be put on flowing.
(4) Two substances are in general use for the purpose of protecting wood against combustion, viz., zinc chloride and soda silicate. Both of these have certain drawbacks. A paint consisting of zinc chloride volatilizes when the material on which it is spread is heated or exposed to flame, and its vapours are unsupportable by human beings. It would therefore be difficult, if not altogether impossible, to enter wooden dwellings painted with the zinc salt when on fire, and thus the salvage of furniture, etc, would be obstructed. The water-glass paint, on the other hand, is liable to be washed away when exposed to rain or other watery influences. Sieburger therefore recalls to mind two fireproof compositions which were formerly in much use. The one is a saturated aqueous solution of 3 lb. alum and 1 lb. copperas, with which the wood is twice pointed; after drying, a solution of copperas in which powdered clay is suspended is brushed over the alum layer. The other protective paint is a mixture of 1 lb. sulphur, 1 lb. clay, and 6 lb. copperas, spread as powder over wood previously washed with a solution of glue. (Ding. Poly tech.
(5) A "fireproof paint," introduced by the United Asbestos Co. of London and Birmingham, is intended to render uninflammable woodwork, etc, which in case of fire forms the main source of supply to the flames. The fire-resi&ting properties of the compound have been thoroughly tested, and the results were satisfactory. A gauze curtain stretched upon a wire frame, and having the name of the company painted upon it, was set on fire, and immediately consumed with the exception of the material so painted, which exhibited only slight symptoms of contact with the flame. Perhaps the most important test, however, was that afforded by two wooden models of theatres, fitted with curtains, proscenium, and all the usual surroundings. One of these was painted over the whole exposed surface with the asbestos paint, the other being left in the ordinary condition. Petroleum was plentifully dashed over both erections, which, being also filled and surrounded by shavings, were then set on fire. In 10 minutes the theatre not treated with the preparation was reduced to a mass of charred timber, whilst the other, though exposed to heat quite as fierce, stood the test admirably.
The painted woodwork was simply blistered; an asbestos curtain was preserved intact; and the asbestos ropes representing those used in the lowering and elevation of scenes, etc, were in no way injured. Finally, several blocks, both of prepared and unprepared wood, were placed upon a coal fire, the blocks painted with the compound resisting the action of the heat for a much longer period than the others, some specimens being shown afterwards as mere shells, of which the interior had all burned away.
(6) Mountford's paint consists of asbestos ground and reground in water, potash or soda aluminate, and potash or soda silicate. When it is to be exposed to the weather, it is combined with oil, driers, and gummy matters, and in some cases with zinc oxide or Larytes. It ia used on the Exhibition buildings at South Kensington, and elsewhere.