The following for tile-work and common brick-crockery, or terra-cotta or porcelain, is very highly commended by Lehner, who says that anything mended with it will sooner break in another place than where it is cemented:—
| Slacked lime | 10 |
| Borax | 10 |
| Litharge | 5 |
The cement is mixed with water, and the tile or crockery, &c., heated just before being mended.
I cannot insist too strongly on this—that no one is to expect that by simply taking recipes, as written, compounding and applying them, there will be a successful result at the first trial. We must always have the best material, often fresh, and generally attempt the application more than once. Perseverando vinces—“By perseverance you will conquer.” Not only must the quality of the ingredients used be of the best, but the composition be made exactly in the order in which they are given. The same substances often give very different results, simply because the order of combination in the two was different.
To repair pavements:—
| Calcined lime | 10 |
| Purified chalk | 100 |
| Silicate of soda | 25 |
This hardens slowly. It can, when mixed with small sharp-edged fragments of broken stone, be used to form pavements, or as a bed for mosaics. For the same purposes, or for cementing marble slabs, a cement known as that of Böttger may be used. It is made thus:—
| Purified chalk | 100 |
| Thick solution silicate of soda | 25 |
This becomes (Lehner) in a few hours so hard that it can be polished. It is the principal, and almost the only, cement used by M. Ris-Pacquot, or commended in his work on mending crockery. It admits of a great variety of modifications. It is very superior as a bed for mosaics of all kinds. It forms, like the preceding, also a good bed for scagliola and ceresa.[1] I would here say of the latter, that I could wish to see it more generally used for mural or wall ornament, since any one who can paint a face or decoration boldly and largely in oil or water colours will find it very easy. It admits of rapid execution, and is striking from its brilliancy. Everything in it depends on having a good bed to which it can easily adhere. I may here observe that beds like these which set hard and fine are also adapted to fresco-painting, in which the difficulty is to select colours which, when absorbed and dried, do not fade. Most paints made from mineral substances combine with silicate of soda.
I may here remark that a curious and easy art, very little known, consists of carving or cutting low reliefs on tiles or terra-cotta or brick-like ware, which, when outlined or in relief, can be glazed in colour with silicate of soda; also with many other cements.