East Indian jewellers never touch silver ware with any abrasive substance, but use, instead of polishing paste, etc., slices of lemons; the goods to be cleaned are well rubbed with these, and then left in a pan for a few hours, covered with slices. For delicate jewellery, a large lime is cut in half, the article inserted, the two halves applied together and tied up for some hours; the article is then washed in several waters, placed in a pan of nearly boiling soapsuds, stirred about, rinsed, and dried on a metal plate, the smooth parts being gently rubbed with washleather, if required. Cyanide of potassium solution (rather weak) dissolves off the dirty surface gradually, but great care is required. Green tamarind pods (oxalate of potash) are greater detergents for gold and silver than lemons, and are often employed for the purpose of removing stains, fire-marks, etc. ('Boston Journal of Chemistry.')
Elsner states that a polish equal to that obtained by the use of the finest plate powder, can be produced by simply cleaning the silver in water in which potatoes have been boiled.
Dead or engraved silver goods should never be cleaned with plate powder, but be washed out with a soft brush and some strong alkali, and well rinsed afterwards. When the dead or frosted parts are quite dry, the polished parts are carefully cleaned with powder.
The following directions are given by a silversmith in Christiania: Silver filigree work is best cleaned by the application of spirit of ammonia by means of a soft brush, and afterwards thoroughly washing in soft-soap and warm water, and rinsing in clean warm water, and quick drying by linen rags, blotting-paper, or some similar clean absorbent. Should this method, after several repetitions, cease to have the required effect, the article will have to be sent to a silversmith to be heated and boiled in acid. The best mode of preservation is to wrap the article in tissue paper before placing it in the case.
The simplest and cleanest substance for cleaning silver articles is, according to Professor Davenport, hyposulphite of soda. It acts quickly, and is inexpensive. A rag or a brush, moistened with a saturated solution of the salt, cleanses even strongly oxidised silver surfaces in a few seconds, without the application of any polishing powder.
Mix 8 oz. prepared chalk, 2 oz. turpentine, 1 oz. alcohol, 4 dr. spirits of camphor, and 2 dr. liquor of ammonia. Apply this mixture to the article with a sponge, and allow to dry before polishing.
Dissolve 12 oz. cyanide of potassium in 1 qt. of water; dip the silver in this solution, and brush it with a stiff brush until clean, then wash and dry.
Tarnished silver lace. Sponge over with a weak solution of potassium cyanide.
Dab over with a cream of heavy magnesia and water, allowing this to dry, and then brushing it off with a soft-haired brush.
Take an ounce each of cream of tartar, muriate of soda, and alum, and boil in a gallon or more of water. After the plate is taken out and rubbed dry, it puts on a beautiful silvery whiteness. Powdered magnesia may be used dry for articles slightly tarnished, but if very dirty it must be used first wet and then dry.
Ordinary petroleum or paraffin will remove the hard blackened surface of old dirty silver goods, and is useful in dealing with goods of intricate design which cannot be rubbed. After soaking the silver in petroleum about an hour, the blackened surface will come off at the least touch. A soft brush can be used, after which use plenty of dry whiting to absorb any remaining oil and to remove the odour.
Silvered dial-plates. Silvered dial-plates of clocks frequently lose their lustre by the effect of air and smoke or sulphurous emanations. To cleanse them make pulverised purified tartar into a paste with water. Take some of the paste on a brush of bristles, and rub the dial-plate, turning it constantly until the silvering has acquired its original whiteness and lustre. Then wash the dial-plate with clean water, and dry by gently patting with a cloth. Finally expose to a moderate heat.
Pickle for frosting and whitening silver goods. Sulphuric acid, 1 dr.; water, 4 oz.; heat the pickle, and immerse the silver in until frosted as desired; then wash off clean, and dry with a soft linen cloth, or in fine clean sawdust. For whitening only, a smaller proportion of acid may be used.