Lime and Egg Cement

231. Lime and Egg Cement is frequently made by moistening the edges to be united with white of egg, dusting on some lime from a piece of muslin, and bringing the edges into contact. A much better mode is to slake some freshly-burned lime with a small quantity of boiling water; this occasions it to fall into a very fine dry powder, if excess of water has not been added. The white of egg used should be intimately and thoroughly mixed, by beating, with an equal bulk of water, and the slaked lime added to the mixture, so as to form a thin paste, which should be used speedily, as it soon sets. This is a valuable cement, possessed of great strength, and capable of withstanding boiling water. Cements made with lime and blood, scraped cheese, or curd, may be regarded as inferior varieties of it. Cracked vessels, of earthenware and glass, may often be usefully, though not ornamentally, repaired by white lead spread on strips of calico, and secured with bands of twine. But, in point of strength, all ordinary cements yield the palm to Jeffery's Patented Marine Glue, a compound of India-rubber, shellac, and coal-tar naphtha. Small quantities can be purchased at most of the tool warehouses, at cheaper rates than it can be made. When applied to china and glass, the substances should be cautiously made not enough to melt the glue, which should be then rubbed on the edges so as to become fluid, and the parts brought into contact immediately. When well applied, the mended stem of a common tobacco-pipe will break at any other part, in preference to the junction. The colour of the glue unfortunately prevents its being used.

The Red Cement

232. The Red Cement, which is employed by instrument makers for fomenting glass to metals, and which is very cheap, and exceedingly useful for a variety of purposes, is made by melting five parts of black resin, one part of yellow wax, and then stirring in gradually one part of red ochre or Venetian red, in fine powder, and previously well dried. This cement requires to be melted before use, and it adheres better if the objects to which it is applied are warmed. A soft cement, of a somewhat similar character, may be found useful for covering the corks of preserved fruit, and other bottles, and it is made by melting yellow wax with an equal quantity of resin, or of common turpentine (not oil of turpentine, but the resin), using the latter for a very soft cement, and stirring in, as before, some dried Venetian red. Bearing in mind our introductory remarks, it will be seen that the uniting broken sub-stances with a thick cement is disadvantageous, the object being to bring the surfaces as closely together as possible. As an illustration of a right and a wrong way of mending, we will suppose a plaster of Paris figure broken; the wrong way to mend it is by a thick paste of plaster, which makes, not a joint, but a botch. The right way to mend it, is by means of some well-made carpenter's glue, which, being absorbed in the porous plaster, leaves merely a film covering the two sufaces, and, if well done, the figure is stronger there than elsewhere. On carefully reading over our article, we find one useful sub-stance has been omitted, namely, what is termed mastic cement, which is used for making a superior coating to inside walls, and which must not be confounded with the resin mastic. It is made by mixing twenty parts of well-washed and sifted sharp sand, with two parts of litharge, and one of freshly-burned and slaked quick-lime, in fine dry powder. This is made into a putty, by mixing with linseed oil. It sets-in a few hours, having the appearance of light stone; and we mention it, as it may be frequently employed with advantage in repairing broken stone-work (as stairs), by filling up the missing parts. The employment of Roman cement, plaster, etc, for masonry work, hardly cowes within the limits of Domestic Manipulation.