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Tinning

Brass and copper articles boiled in a solution of stannate of potassa, mixed with turnings of tin, are in a short time covered with a layer of pure tin. If the articles be boiled in caustic alkali or cream of tartar with tin-powder, the same effect is produced; the latter mixture is composed of water 2 pails, cream of tartar 1/2 lb., salt 1/2 pint. Keep the article moving throughout the process.

Copper tubes may be tinned inside by a solution of salts of tin added to the solution of Rochelle salts, which forms a precipitate of stannous tartrate, which must be washed and then dissolved in caustic lye. Rinse the copper tube with sulphuric acid, and afterwards wash it well out, after which the tube must be filled with the alkaline solution, slightly warm, and a tin rod inserted; the latter will at once cause a thin coat of metallic tin to be deposited.

Iron pots and similar articles are first cleaned by immersion in sulphuric acid and water for new metal, and muriatic acid and water for old metal, with a subsequent scouring with sand, followed by washing in water. They are then put into a bath prepared with cream of tartar 1 ounce, protochloride of tin 1 ounce, water 10 quarts. This bath is kept in a wooden or stone-ware vessel at a temperature of 190 deg. Small pieces of zinc are distributed among the articles in the bath, which may be taken out and washed with water when the coat of tin deposited thereon is thick enough.

If iron articles are first cleaned as above, they may be made hot enough to melt tin, and then rubbed with salammoniac, as well as sprinking the latter (in powder) over them; the tin can then be applied, and as it melts be spread evenly all over with a hand-cloth.

A cold process of tinning is to blend tin-foil and mercury into a soft, fusible amalgam, and, after cleaning as before directed, rub on the amalgam while the article is moist, and then apply heat to evaporate the mercury. See TIN-PLATE.