posted 12-03-2017 12:15 PM            

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ELECTROLYTIC CLEANING OF SILVERWARE

A bulletin recently published by the U. S. Dept. of Agriculture deals with the electrolytic method of cleaning tarnished silver, which is recommended as an easy and effective way of performing this task. It consists in boiling the article in a soda and salt solution in contact with a clean piece of aluminum or zinc. Experiments made under the direction of the bureau showed that when silver spoons were polished with whiting paste, nearly .01 gram of silver each was lost, whereas with the electrolytic process, only one-twenty-fifth of this amount was wasted.

The theory of the process is explained as follows: The tarnish which occurs on silver is not due to oxidation, but to the action of sulfur. The electrolytic cleaning method depends on the facts that this tarnish of silver sulfide is slightly soluble in the hot solution employed, and is broken down chemically and its silver content redeposited on the ware when the proper electrical conditions prevail. The presence of both the silver and the aluminum or zinc in the hot solution provides the necessary electrical conditions, practically all the silver in the tarnish being returned to the object cleaned. When the silver polishes are used, on the other hand, all the silver in combination in the tarnish is removed.

In the cleaning method recommended by the department, the necessary materials are a graniteware cooking utensil deep enough to allow the silverware to be covered by the solution; a clean piece of aluminum or zinc, preferably the former and baking or washing soda. The solution, consisting of a teaspoonful of baking or washing soda and a like amount of table salt to each quart of water, is brought to a boil in a graniteware or enameled utensil. A sheet of aluminum or clean zinc is dropped in. The tarnished silverware is then immersed in the solution so that it is in contact with the sheet of aluminum or zinc. The tarnish should disappear in a few seconds. The silver objects should then be removed from the solution, rinsed, and dried with a soft cloth.

Aluminum is much more satisfactory than zinc for use in this cleansing process, since it does not become coated with a layer of carbonates which would interfere with the chemical reaction. Zinc docs form carbonates and, if used, must be cleaned frequently in dilute hydrochloric acid.

The utensils used for this purpose should not be used later in cooking operations. The method is most effective when the solution boils during the cleaning process, and efficiency is rapidly lowered as the temperature of the solution falls below the boiling point. The electrolytic method gives the cleaned silver a satiny finish after several cleanings. If a burnished surface is desired, the silver must from time to time be polished lightly with some abrasive material, such as powdered whiting.

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