Formulary's Silver Intensifier is equivalent to Kodak In-5 and Du-Pont 3-I. The intensifier acts by depositing silver metal on existing silver grains in the emulsion. The amount of new silver deposited is somewhat proportional to the amount of silver originally present in the negative. The intensified image is permanent, has greater contrast than the original negative, and can be toned. The intensifier is used in room light and the extent of intensification is determined by inspection of the negative as intensification is taking place. After the negative has been intensified sufficiently, it must be fixed and washed.