Rapid developer for black and white films - contains hydroquinone, developer, potassium bromide, sodium hydroxide and sodium sulphite

摘要

Developer for black and white films comprises (by wt. on total active material = 100%) 16-23 (19-21)% hydroquinone, 23-30 (26-28)% of a developing agent chosen from Metol and Elon, 24-31 (27-29)% KBr and 24-32 (27-29)% NaOH. The developer also contains from 1/3 to three times the wt. of active material of Na sulphite as preservative, and sufficient water to form an aq. soln. of the active material. The developers are pref. made by dissolving the active part and the preservative in water at 38-54 degrees C. such that the amt. of active material remains at 5 wt.% of the amt. of water. After dissolving the components, the developer is diluted with water until the soln. contains 5 (0.5-5)% active material w.r.t. the wt. of water. The developers allow rapid development of black and white films without loss of negative quality, and the developers have good keeping properties.