Stilwell, Katharine Marian · Chicago, New York, Rand, McNally & Company · leaf 133
sable to make a fresh solution of nitricacid. Shaking the tray will hasten the etching.When the plate is etched deeply enough—thatis, when the ridges stand up enough for print-ing—it should be taken out of the bath andthe varnish removed. The plate may be heatedto soften the varnish, and then… … Fig. 49. Zinc etching made by elementary-school pupils of the Bloomington, Illinois,Public School 116 CHAPTER XIVPAPER While all paper is made according to the samegeneral plan, various Mendings of the materialsand modifications of the machinery used enablethe manufacturers to produce many kinds of…
Printing
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