Polytechnic Association. 787 



as the coating dries, smoothing it by means of blenders — the long- 

 haired brushes used by artists for similar purposes. When thoroughly 

 dry, and, of course, completely covered with the color, the glass is 

 ready to receive the pattern. The protecting plate or design plate 

 now comes in use. It is laid upon the glass, to which it must fit very 

 closely, and the superfluous enamel brushed away through the inter- 

 stices of the pattern ; a complete inversion of stencil work, where the 

 color is put on through the plate. The glass goes at once to the kiln 

 to be heated or " fixed," so that the enamel, which is a little more fusi- 

 ble than the glass, melts, combining with the glass, so that the pattern 

 becomes as indestructible as the glass itself. 



These are the outlines of a process which has had its origin and 

 growth in the glass trade, and, so far as the writer knows, has never 

 been practiced outside of that trade. It becomes a matter of no 

 small importance to consider whether as valuable a process may not 

 be applied to decorative and preservative arts, and have a wider range 

 of use than it has at present. 



In the consideration of the topic, it may be well to consider first 

 how these plates are made. 



When the sheet brass comes from the manufactory it is rolled up, 

 and when spread out again is very rough and uneven. If made into 

 a plate in that condition it would be utterly useless. It must, there- 

 fore, be stretched and rolled until it is perfectly flat. Ordinarily the 

 sheet of metal is then covered with wax, and the lines requiring to 

 be cut through are etched with acid. They cannot be cut as in stencil 

 work, because the action of the punch or tool would so tear and injure 

 the edge of the metal, that it would no longer fit closely upon any 

 surface to which it might be applied. After the acid has cut entirely 

 through the metal, the edges are carefully trimmed with a knife, and 

 the protecting plate is ready for use. 



Many of the colors, when applied to the glass, have no resemblance 

 to the intended tint. When heated, however, chemical changes take 

 place and the desired color appears. This piece of glass which I 

 show you now, is covered with what will be black enamel, when it is 

 burnt in ; at present it is only a dark olive green. Nitrate of silver 

 produces a brilliant transparent yellow, but when put on to the glass, 

 is a dirty gray color. 



The other day, when showing these plates to a gentleman, very wise 

 in his own conceit, he remarked, " oh, yes," he had made such stencils 

 many years before. They were for etching with acid. A remark 

 which he no doubt deemed very wise, but which showed that he knew' 



