Formulary's TD-16 or Improved D-76 is formulated to duplicate working characteristics of Kodak D-76 precisely. D-76 is probably the most popular black and white developer in the world. It offers optimum balance of speed, fine grain, high sharpness and good gradation. One important way TD-16 differs from D-76 is consistent results. The pH of D-76 can rise considerably and contrast is greatly increased. They have worked out a proprietary modification of D-76 that maintains all its desirable working characteristics over a period of six months.