Sunday, April 19, 2009

Silver Plating Result

Silver is, of course, a beautiful white and highly reflective metal, which is intrinsically resistance to most corrosive influence, especially to fruit acids and foodstuffs. It is, unfortunately, readily tarnished to a most disfiguring dark-brown or black sulphide by the action of hydrogen sulphide in the air or by sulphur compounds in foodstuffs. This tarnish is superficial and does not involve much depth of silver. Silver is therefore the ideal electroplate for household and tableware, and now that detarnishing dips are available the tarnish question is not serious. Since the basis metal is always intrinsically corrosion resistant and the conditions of exposure are not severe, thin coatings are sufficient on articles not subject to much abrasive wear. For table article such as spoons and forks, however, a much thicker coating in necessary to avoid penetration in use. Most reputable silver platters therefore apply relatively thick coatings in excess of 0.001 in to such articles. However, since silver is an expensive metal the tendency is to express the amount applied by quoting the weight of silver per article or per dozen, which confuses the issue unless the area of electroplate is known.

Some ingenuity is often devoted to shielding articles in the plating bath in such a way that a thicker deposit is preferentially applied to places where most wear is to be expected, such as fork prongs and the backs of spoon bowls. In many case silver and all other metals plated from double cyanide electroplating solutions have very good throwing power i.e. the thickness of plating is better in recesses that might be expected.

Silver plating is now increasingly used for electronic parts and for some bearings where use is made of the high electrical and thermal conductivity of the metal respectively.

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