The Edwal TST Developer Part A is a flexible black and white paper developer, which produces a wide range of monochrome shades from cold to warm black.This developer is recommended to be used at a temperature ranging from 55 to 90 degree FahrenheitFor heavy-duty applications, 1 gallon of TST can be used to produce 12 gallons1 gallon of TST can also diluted to 16 gallons as a commercial strength developer, and 20 gallons as a portrait strength developerThe portrait strength developer can develop over 4,000 - 8 x 10 prints