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Vitrum Annulare, Pastes

Zmilampis, Cat's-eye Page of 453 Vitrum Annulare, Pastes Text size:minus plus Restore normal size   Mail page  Print this page
344
VITRUM ANNULARE.
" Paste," from the Italian pasta, is most strangely changed from its primary meaning. Who could discern any analogy between a bit of glass and dough, the proper sense of the word ? It comes in fact from pastus, food ; and the grand staple of the Southern Italian's dinner has been from time immemorial the dough of the gran duro (the ancient far) moulded into all kinds of curious forms, but all going under the generic name of paste. From the same root springs the pâte of the French, and our own pasty, which varies less from the original. Hence the Italians, when they revived the fabrication of imitative gems, applied to the softened plastic material the familiar household word.
Pastes are imitations in glass of the precious stones, and also of engraved gems, camei and intagli, transparent and opaque ; and the process of the manufacture is the following :—A small iron case of the diameter required is filled with a mixture of fine tripoli and pipeclay moistened, upon which is made an impres­sion from the gem to be copied. This matrix is then thoroughly dried, and a bit of glass of the proper colour laid fiat upon it. If a stone of different strata has to be imitated, so many layers of different-coloured glass are piled upon each other. The whole is next placed within a furnace, and watched until the glass is just beginning to melt, when the softened mass is immediately pressed down upon the mould by means of an iron spatula coated with French chalk, in order to prevent adhesion. It is then removed from the furnace, and annealed or suffered to cool gradually at its mouth, when the glass, after cleaning out, will be found to have taken a wonderfully sharp impression of the stamp upon the tripoli, but in reverse, whether the prototype be in relievo or incavo. When a cameo is the model, all the undercutting must
Zmilampis, Cat's-eye Page of 453 Vitrum Annulare, Pastes
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