Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Management
Those who have never used the cyanide bath may desire some additional particulars regarding its management. The anodes in such a bath generally carry a slight greenish coating, consisting of copper cyanide. This is soluble in the free cyanide that is in the bath, and only traces of it should appear on the anodes. When the cyanide is used up, this green coating thickens up rapidly, and the bath, shortly afterwards, stops depositing. In such case, add cyanide (dissolved in water) very slowly, in order not to get in too much.
If too much cyanide is in the bath, bubbles of hydrogen will come from the objects to be coated, but no copper will be deposited, and the remedy is adding carbonate of copper.
If either of the above does not give a rapid and even coating, the bath needs more metal, and you are likely using too small an anode and stripping your bath. The remedy is, of course, found in adding more carbonate and using a larger anode.