WATER-GLASS PAINTING, a method of painting in which the vehicle, or binder of the colours, is a soluble alkaline silicate. This process, which has been in use for some years in Germany for mural painting, and in which Kaulbach, among others, has painted all his later wall-pictures, appears to have been invented, or greatly improved, by Dr. Johann N. Von Fuchs, who termed it Stereoeltromy, and pub lished a pamphlet explanatory of the process and pointing out its advantages. This bas been translated for private circulation by direction of the Prince Consort (chiefly with a view to the consider ation of the applicability of the process to the paintings in the New Palace at Westminster), under the title of ' The Manufacture, Pro perties, and Applications of Water-Glass (soluble alkaline silicate), including a Process of Stereochromic Painting.' Mr. D. MacRae, ILA., who was engaged on the preparatory labours connected with painting in fresco a large picture, ' The Meeting of Wellington and Blucher,' in one of the two spaces (45 feet in length) in the Royal Gallery of the House of Lords, and who had been greatly impressed with the failure, as regards permanency, of the recently-painted frescoes, was led by a permed of this pamphlet to determine on submitting the water-glass process to a searching investigation. He accordingly made various experiments, and, not succeeding to his satisfaction, proceeded to Germany to make himself acquainted with the method as actually practised there, and to examine the works executed. The result was his conviction of its suitability. Ile has since executed various trial pictures, and be is now painting his great picture with water-glass.
Mr. J. R. Herbert, R.A., who is engaged in painting the Peers Robing Room, also, having," after repeated experiments, modified it according to his own views," expresses himself entirely satisfied with it. Ae its working capabilities have so far satisfied the practical artist, and the finished examples appear to have withstood successfully not only the effect of time,—as yet too brief to be conclusive,—but also the various tests hitherto applied, the process would seem to merit very attentive consideration. The frescoes painted within the last few years, not
only in this country, but in Germany, where so much more attention has been given to them and artists are so thoroughly familiar with all the working details, have for the most become deteriorated to a very marked extent ; and it will be an immense gain if the water-glass process proves to be a really permanent, as it would seem to be in other respects an efficient, substitute. It will be no doubt interesting to give a brief general statement of the process; for further particulars we refer to the Twelfth Report of the Commissioners ou the Fine Arts' (1861), in an appendix to which Mr. Mediae has given a very full account of his experience and ample details of the modes of working.
The Water-Glass is composed of powdered quartz (silica) boiled in purified potass or soda, but, according to Dr. l'etteukofer, the chief authority on the subject, the potass solution is to be prefernaL It is prepared by chemists of different degrees of strength, according as it is to be employed for Leying-on the colours or for fixing. The pigments are the same as those used in fresco-painting, but zinc-white is 'the only white that can be relied on. The ground is an intonaco, formed of river-sand and Portland cement, precisely as for FRESCO, but some what more absorbent. Kaulbach has the ground prepared with a granulated surface, insisting that " it should feel to the touch like a coarse rasp ;" but this does not appear to be necessary. A smooth ground, if carefully prepared, takes the colours with equal facility ; and, in fact, the degree of roughness or smoothness may be regulated at the plmeure and according to the manner of the painter. After the intonaco has been well dried, and the cement hardened, the superficial sand is to be swept off, and the surface to be moistened with a saturated solution of carbonate of ammonia (Mr. Maclise, we believe, employs lime-water). when it is ready for painting on.