Book 3 — Heater Keeps Developer at Proper Temperature
Reading edition
Having had trouble with developer cooling down and failing to work properly, while developing in the dark room, I constructed the apparatus shown. A small light-tight box was made slightly larger than the tray, with a removable top having an opening to hold the tray. An electric-light socket was fastened inside at one end of the box and a lamp fitted to it. A wire was attached across the middle of the lower side of the box, so that the latter and the tray could be rocked. The box was lined with black paper and varnished black. The edges of the opening in the top were fringed with felt to guard against light leakage. A thermometer is used to determine the temperature. When the developer cools, turn on the light until it reaches the required temperature.—John Hoeck, Alameda, California.
