among artificers, a tenacious viscid matter, which serves as a cement to bind or connect things together.
Glues are of different kinds, according to the various uses they are designed for, as the common glue, glove-glue, and parchment glue; whereof the two last are more properly called size.
The common or strong glue is chiefly used by carpenters, joiners, cabinet-makers, &c., and the best kind is that made in England, in square pieces of a ruddy brown colour; and, next to this, the Flanders glue. It is made of the skins of animals, as oxen, cows, calves, sheep, &c., and the older the creature is, the better is the glue made of its hide. Indeed, whole skins are but rarely used for this purpose, but only the shavings, parings, or scraps of them; or the feet-sinews, &c. That made of whole skins, however, is undoubtedly the best; as that made of sinews is the very worst.
The method of making Glue. In making glue of parings, they first steep them two or three days in water; then washing them well out, they boil them to the consistence of a thick jelly; which they pass, while hot, through oyster-baskets, to separate the impurities from it, and then let it stand some time, to purify it further: when all the filth and ordure are settled to the bottom of the vessel, they melt and boil it a second time. They next pour it into flat frames or moulds, whence it is taken out pretty hard and solid, and cut into square pieces or cakes. They afterwards dry it in the wind, in a sort of coarse net; and at last string it, to finish its drying.
The glue made of sinews, feet, &c., is managed after the same manner; only with this difference, that they bone and scour the feet, and do not lay them to steep.
The best glue is that which is oldest; and the surest way to try its goodness, is to lay a piece to steep three or four days, and if it swell considerably without melting, and when taken out resumes its former driness, it is excellent.
A glue that will hold against fire or water, may be made thus: mix a handful of quicklime with four ounces of linseed oil; boil them to a good thickness, then spread it on tin-plates in the shade, and it will become exceeding hard, but may be easily dissolved over a fire, as glue, and will effect the business to admiration.
Method of preparing and using Glue. Set a quart of water on the fire, then put in about half a pound of good glue, and boil them gently together till the glue be entirely dissolved and of a due consistence. When glue is to be used, it must be made thoroughly hot; after which, with a brush dipped in it, besmear the faces of the joints as quick as possible; then clapping them together, slide or rub them lengthwise one upon another, two or three times, to settle them close; and so let them stand till they are dry and firm.