A LUTING for very high temperatures:—
| Clay | 100 |
| Glass powder | 2 |
Another CEMENT:—
| Clay | 100 |
| Chalk | 2 |
| Boracic acid | 3 |
Lehner has in his work on Cements many valuable suggestions as to mending porcelain. Firstly, that in such mending, the adhesive be applied with care, in as even and as thin a coat as possible; to which I would add, that the unskilful amateur is apt to daub it on irregularly and carelessly, with the impression that the more cement there is the better it will stick, which is just so far wrong that every superfluous grain is just so much of an impediment to good drying or adhesion. Again, the inexpert daubs it on with a stick or “anything,” when a fine-pointed brush or hair-pencil should be used.
Broken china which is to be mended should be carefully covered away so as to protect it from dust, which is hard to clean off. Beware of fitting the pieces together again and again, as is often done.
If the broken china was used to contain milk or soup, &c., it should be laid in lye to dissolve all the fatty substance, and then be washed with clear water. Painted porcelain cannot, however, be laid in lye, which would ruin all the colours; in this case wipe them clean with dilute acid.
The great difficulty in mending is to bring the pieces together and keep them so till the adhesive dries. Lehner recommends that when objects are small and costly, a mould of gypsum be constructed round them. In most cases putty or wax is far more manageable. As before remarked, indiarubber bands are chiefly to be relied on; even if not capable of holding permanently, they aid greatly in tying with cord.
In the Manual of F. Goupil, rewritten by Frederick Dillaye, the following method of restoring broken vases, &c., is commended:—
“Form a solid mass of clay in the form of the original object. Then place on it, one by one, the fragments in their place, keeping the clay moist. When this is done, paste over the exterior strips of paper, in sufficient quantity to hold the whole firmly together. Then remove the moist clay, and paste strong slips of paper” (or thin parchment) “over the interior so as to hold the whole. Then” (when dry) “carefully moisten and remove the outer coating.”