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.
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To Clean Metal Dials
Silver and gold dials can be restored by gently heating the back over a spirit lamp and dipping the dial in diluted nitric acid. If the figures are painted however, they will be removed, and it will be necessary to repaint them, but if they are enameled on, the enamel will not be injured. If the figures are painted the dial may be cleaned by brushing with powdered cream of tarter either dry or in the form of a paste mixed with water. Avoid all the painted portions and work the paste in between the painted portions with a pointed peg wood. Wash with warm water and dry by carefully patting with a soft linen rag.
To Grind Enamel from the Back of Dial. It is sometimes necessary to remove a portion of the enamel from the back of a dial to allow room for the motion work, etc. The most convenient method is to grind the back with emery, preferably in the shape of a wheel. Water should be applied to the work from time to time to prevent heating.