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tel 212 995 0395 Darius Adhesives A scarce number of adhesives have been used until the XXth century, and among them, hide and bone glue have been the most important on account of their excellent mechanical properties and availability. Both of them consist mainly of the animal protein collagen, which is extracted from the skin, cartillages and bones of mammals such as cows, horses and sheep, being the best the one from cows. The real one is sold dry and as light amber pellets or thin sheets and must be prepared by the user, ensuring its purity. It is prepared by soaking it in a little amount of water for some hours and then warming it in a double recipient with water in between, to prevent the glue from boiling. The perfect density for general use is a flowing honey-like consistency and must be applied hot, over hot surfaces. This peculiar technique is due to the reversible colloid property of animal glue, which is liquid between certain temperatures; if the glue or the surfaces are colder than that. it acquires a jelly consistency that makes it impossible to use. It is applied with stiff brushes or syringes and in moderate quantity. Just a little is enough to make a very strong link, stronger than the glued surfaces themselves. The main use of this adhesive is to glue structural parts of furniture, marquetry, other organic materials (tortoiseshell, ivory, leather) and structure and surface replacements. It is not recommended for metal, plastic or vitreous materials. As it takes several hours to set, surfaces glued with hide glue or bone glue must be clamped, but with a moderate pressure; strong pressure takes most of the glue out, leaving a film so thin that the link becomes unstable and extremely sensitive. The only disadvantage of hide and bone glue is their sensitiveness to constant changes of humidity and to biological attack (fungi and bacteria). Alternative materials are synthetic and they are: PVA (polivynil acetate), acrylic methacrilate and cyanoacrylic compounds but all of them have certain disadvantages. For these reasons hide and bone glue are the best and safest choices. |
1999 Darius Gubala