THE PROOESSES OF PURE PHOTOGRAPHY.
163
DEFECTS .AND REMEDIES.
Insolubility of tisme, due to drying in wann damp air. Acid sensitizing bath. Too long keeping after sensitizing. Bichromate bath decomposed. Actinic light and "eontinua• tive a.Ction.'' The ti8me melts in the sensitizing bath. Too high temperature. Ice the solution or replace twenty-five per cent. of the water with alcohol The ti8sue becomes hard or crackly. Air too dry. Keep in a damp place or add a very little glycerine to sensitizer. The prints refuse to adhere to temporary mpport before development. If at edges only, want of "safe edge." If all . over, tissue insoluble. Or the tissue allowed to remain too long in the plain water before squeegeeing to temporary support. A.s the swelling of the gelatine causes the adhesion, it is evident that if the swelling is complete before squeegeeing no adhesion can ret~ult. Insufficient time allowed under the weight. Spots.-Perhaps due to air bells between tissue and support. Air bells are very apt to form in the cold water bath ; they must be watched for and removed. Reticulation, or an appearance of " grain " in the image. A mysterious and not uncommon defect, due probably to incipient insolubility. Remedy: Observe all the precautions suggested for cases where the tissue refuses to adhere to temporary support. The prints with their final support refuse to l8olve the temporary support. Imperfect waxing or talcing.