Important: Safety Warning
This page contains a formula or preparation using substances now known to be dangerously toxic, such as arsenic, mercury, lead, or cyanide compounds. Exposure to these substances can cause severe poisoning, permanent injury, or death.
In addition, 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.
Green Gold
Add cyanide or chloride of silver to the gold bath, until it assumes the desired color; or suspend silver anodes beside the gold anodes. Coloring is always done with pure gold, and the best workmen take especial pains to see that no silver or copper is allowed in the solution. They do this by using only the best chemicals, and frequently evaporating their baths and parting out the silver with nitric acid. By this means they obtain an immense advantage over others, in the brightness and thinness of the coating of gold deposited.
The durability of gold plating does not depend altogether on the time it is in the solution. If the current is about two to three volts (about equal to a Bunsen cell, or two Smee cells connected, for intensity) and the quantity is proportioned to the work in the bath, then if the solution be worked at 120 deg. to 130 deg., which also deepens the color of the deposit, it is possible to get a coat inside of five minutes that will last for several years. It is always best, when other conditions are all right, to keep the work moving, and immerse the gold anode gradually, to suit the surface to the work that is being plated; care should be taken not to allow the work and anode to touch each other, as a black or burned spot will be left on the work wherever the anode touches it.
After getting the first slight coat of gold, the work should be scratch brushed with a fine brass scratch brush (wire about .003 inch), letting a little soap suds drip on the brush. This lays down the fist coat of gold, which should be sufficient to cover the article entirely. The scratch brush acts as a burnisher. After this it is thoroughly cleaned of the soap suds in hot water, and again placed in the solution. The time it remains will have to be governed by experience, but generally five minutes will give a sufficient coat to stand burnishing.
Burnishing may be done with steel and agate burnishers, same as with silver, or the articles may be polished with a soft cotton flannel wheel, run at 2,500 revolutions per minute, and bearing a very little of the finest rouge, mixed with alcohol. If you run your wheel too slow the layers of cotton will not stand up, and you will not get a polish; 2,500 to 3,000 revolutions is about right, and the pressure should be light and even.