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.
Pickle
A pickle for removing sand from castings by sprinkling is made from sulphuric acid 1 and water 4. The castings are sprinkled and exposed to the atmosphere when this is used; but if it is desired to make a bath in which to submerge the castings, then 10 of water may be added to 1 of the acid. For cleansing brass castings the pickle should be made from nitric acid 1 and water 3.
The vessel in which the sulphuric-acid pickle is to remain should be lined with sheet lead; that for the nitric-acid bath should be of earthenware or glass.
Cast-iron work should receive considerable attention after pickling, if it is intended to plate or japan them. The gray accumulation seen on the surface after this process will, if left thereon, be sure to fall off in time, bringing with it whatever has been subsequently applied. Simple water is not sufficient to accomplish a thorough cleansing from this objectionable film; the castings should be first steeped in a strong hot potash or soda bath, after which hot water or steam may be played over them until they are thoroughly clean, when after being heat-dried they are ready for the plating, japanning, or paint. See PLATING; DIPPING; LACQUERING.