. The book of photography; practical, theoretical and applied. Fig. 141.—Pneumatic Holder and Glass Platk. frilling. Frilling is probably one of themost serious troubles the experimentalplate maker will have to contend consists of an iiTCgular expansion of thegelatine around the edges of the plate,causing it to pucker up and leave the started, unless immediate pains aretaken to harden the film and arrest itsprogress, the latter is liable to completelyleave its support and float off into the solu-tion. The most likely time for such frill-ing to occur is in the hypo, bath, par
. The book of photography; practical, theoretical and applied. Fig. 141.—Pneumatic Holder and Glass Platk. frilling. Frilling is probably one of themost serious troubles the experimentalplate maker will have to contend consists of an iiTCgular expansion of thegelatine around the edges of the plate,causing it to pucker up and leave the started, unless immediate pains aretaken to harden the film and arrest itsprogress, the latter is liable to completelyleave its support and float off into the solu-tion. The most likely time for such frill-ing to occur is in the hypo, bath, particu-larly if the weather is very hot or verycold, or the solutions of imeven temperorture. In bad cases of frilling it will evenstart in the developer. To ensure a properadhesion of the film to the glass is. there-fore, most important. PLATES AND FILMS. G9 Coating the coating in factories is done bymaciiinery, but in experimental work handcoating will answer quite well. It is pos-. Fig. 142.— , FiRST POSITION. sible to coat 60 plates in an hour by hand,and, in fact, until about fifteen years ago,the majority of the work was done in thisway. A pneumatic holder, similar to thatshown in Fig. 140, will be useful. Thisconsists of a collapsible rubber bulb Awith a flat top b. The bulb is pressed,the plate laid on the top, and the bulbreleased, when it holds firm by suction(see Fig. 141). In use, the holder shouldbe placed in warm water until ready, asotherwise the chill is liable to cause a over on to the arm—then finally to thebottom right-hand corner, pouring the ex-cess into the coating pot. Figs. 142 to 145will make this clear. If a certain quantityof emulsion be taken in a warm measure,
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