Gum biochromate is one of the precious photographic techniques characterized by free interpretation. The process involves the use of light sensitivity of chromium salts and the colloidal properties of arabic gum. Prepared emulsion is applied on paper and irradiated through the negative. Due to the operation of the light, chromium oxides are created. They make gum tanned and insoluble in water. The development process takes place in a cell with cold water. Finally an image appears on paper.