. Elementary and dental radiography / by Howard Riley Raper . hour or longer. When several negatives are being made, it is ad-visable to use a washing box similar to the fixing box. (Fig. 74.) * Running water is much to be preferred, as the friction or movement ofthe water is a great factor in cleansing the plate. After a few months, if platesshow cloudiness, or a metallic luster is observed, this means that the plates werenot thoroughly washed. It is even advisable, after washing, to rub the surface ofthe film side with clean, wet cotton, holding the plate under a faucet during the act. So EL
. Elementary and dental radiography / by Howard Riley Raper . hour or longer. When several negatives are being made, it is ad-visable to use a washing box similar to the fixing box. (Fig. 74.) * Running water is much to be preferred, as the friction or movement ofthe water is a great factor in cleansing the plate. After a few months, if platesshow cloudiness, or a metallic luster is observed, this means that the plates werenot thoroughly washed. It is even advisable, after washing, to rub the surface ofthe film side with clean, wet cotton, holding the plate under a faucet during the act. So ELEMENTARY RADIOGRAPHY The next, and the last step in the making of theDrying. negative, is to dry it. The plate should be set on edge. Drying should take place in a clean atmos-phere, so that no dust or soot will fall on and stick to the coated surfaceof the negative. Plate racks (Fig. 75) may be used, but are not a neces-sity. The plate may be set on edge at an angle of about 95 degrees bvsimply leaning it up against some perpendicular wall. (Fig. 76.) Dry-. Fig. 76. Negatives leaning against perpendicular wall, drying. ing requires several hours. It may be hastened by placing the negativein a breeze. By immersing the negative in a mixture of formalin andalcohol, then placing it in the breeze of an electric fan, drying will bevery materially hastened. The use of the formalin and alcohol some-times causes spotting and blurring of the negative. If all the salts ofthe fixer are not well washed out of the emulsion, it will not dry prompt-ly, but will become rough and sticky, and, when finally dry, it will be fullof little holes. Summarizing the making of the negative, it consists of exposing,developing (washing—mere dipping in water), fixing, washing, and dry-ing. If the negative when finished is very dark, so dark that parts of theimage are lost, the plate was either overexposed, or overdeveloped, or MAKING RADIOGRAPHS 81 both. I prefer usually to say that it was overdeveloped,
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