In practical leather coloring, the difficulties that the dyer most frequently meets with in his efforts to get clear, deep and uniform shades may be readily divided into four classes: 1. Those troubles that arise from improper methods of handling the hides or skins in the processes of beamhouse and tannery. 2. Those that spring from faulty preparation of the leather before the dye is applied. 3. Those that are caused by the use of poor grade coloring materials. 4. The difficulties that result from ignorance of the best methods of using the coloring materials, and carelessness or abuse during the actual process of coloring.