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.
Dulled-brass
The dead appearance, by the French styled "mat," is obtained on brass by observing the following: Immerse in nitric acid 200, sulphuric acid (sp. gr. 1.845) 100, salt 1, sulphate of zinc 2. Very large objects should have a mixture of nitric acid 3, sulphuric acid 1, water 1, sulphate of zinc 1/2. Repeat the dipping and well-rinsing till the desired color is imparted. See DIPPING.