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Copper (Perhaps the most useful)

Perhaps the most useful solutions for the plater are the cyanide copper solution, and the cyanide brass or bronze solution. The acid copper solution generally used, which is merely sulphate of copper dissolved in water, is easily made and used, but has numerous disadvantages when compared with the cyanide. It will deposit faster, but leaves a rough and crystalline surface, and cannot be used on steel, as the latter metal is electrically opposed to copper in the presence of sulphuric acid, and sets up a local action which throws off the deposit in scales as fast as it is formed. The cyanide solution deposits a smooth, even and firm coating, takes equally well on steel, brass or other surfaces, and is capable of so many variations that it may be regarded as the basis of all brass, bronze and copper plating. It is also the only sure means of making a firm deposit of silver or gold on steel. Articles of iron or steel should first be given a light coating of copper, and then the gold or nickel will be held firmly, evenly and smoothly, so that lighter coatings of the more expensive metals will wear longer and look better than a thicker deposit directly on the steel. The old formulae for cyanide of copper solutions, all recommend mixing acetate of copper with carbonate and bisulphite of soda, and then adding potassium cyanide to the carbonate of copper thus formed. This encumbers the bath with a number of useless secondary reactions, and makes it liable to get out of order. It is much better to buy carbonate of copper from a dealer in platers' supplies. It is cheaper than the acetate, and does not put anything in the solution which is unnecessary To make the solution, use to each gallon of water: Carbonate of copper_____________________________7 ozs. Carbonate of soda_______________________________2 ozs. Cyanide of potassium (chemically pure)__________8 ozs.

Dissolve about nine-tenths of the cyanide of potassium in a portion of the water, and add nearly all of the carbonate of copper, previously dissolved in a portion of the water; then add the carbonate of soda, also dissolved in water, slowly stirring until thoroughly mixed. If you have a hydrometer, make your solution to 16 deg. B., then put in a small article and test your solution, adding cyanide or copper, or both, until the solution deposits freely and uniformly.

This may be regarded as a stock solution, and if much work is done, it is best to use it as a basis and make others from it, keeping them separate.