3638. To Tin Iron Pots and other Domestic Articles

3638.     To Tin Iron Pots and other Domestic Articles. The articles are cleaned with sand, and, if necessary, with acid, and put then in a bath, prepared with 1 ounce cream of tartar, 1 ounce tin salt (protochloride of tin), 10 quarts water. This bath must be kept at a temperature of 190° Fahr., in a stoneware or wooden tank. Bits of metallic zinc are put into and between the different pieces. When the coat of tin is considered thick enough, the articles are taken out of the fluid, washed with water, and dried.

3639. To Tin by the Moist Way

3639.     To Tin by the Moist Way. Make a solution of 1 part protochloride of tin in 10 parts water, to which add a solution of 2 parts of caustic soda in 20 parts water; the mixture becomes turbid, but this does not affect the tinning operation, which is effected by heating the objects to bo tinned in this fluid, care being taken, at the same time, to place in the liquid a piece of perforated block tin plate, and to stir up the fluid during the tinning with a rod of zinc.

3640. To Tin Iron Without the Aid of Heat

3640.    To Tin Iron Without the Aid of Heat. To 105 quarts water are added 61/2 pounds rye meal; this mixture is boiled for 30 minutes, and next filtered through cloth; to the clear but thickish liquid are added 233 pounds pyrophosphate of soda, 371/2 pounds protochloride of tin in crystals (so-called tin salt), 1471/2 pounds neutral protochloride of tin, 3i to 4 ounces sulphuric acid; this liquid is placed in well made wooden troughs, and serves more specially for the tinning of iron and steel wire (previously polished) for the use of carding machines. When, instead of the two salts of tin just named, cyanide of silver and cyanide of potassium are taken, the iron is perfectly silvered.

3641. To Cleanse Iron for Tinning

3641.    To Cleanse Iron for Tinning." The metal must be cleansed by immersion in an acid solution; for new metal, this solution should be sulphuric acid and water, but for old metal, muriatic acid and water; next scour with sand, and cleanse well with water.

3642. To Tin Iron

3642.    To Tin Iron. First cleanse as above, then heat the article just hot enough to melt the tin, rub the surface over with a piece of sal-ammoniac, and sprinkle some of the sal-ammoniac in powder over it; then apply the tin and wipe it over evenly with a piece of tow.

3643. Cold Tinning

3643.     Cold Tinning. Rub pure tinfoil and quicksilver together until the amalgam becomes soft and fusible, clean the surface to be tinned with spirits of salt (hydrochloric acid), and, while moist, rub the amalgam on, and then evaporate the quicksilver by heat.

3644. Stolba's Method of Tinning Copper, Brass, and Iron in the Cold, and

3644.      Stolba's Method of Tinning Copper, Brass, and Iron in the Cold, and. without Apparatus. The object to be coated with tin must be entirely free from oxide or rust. It must bo carefully cleaned, and care be taken that no grease spots arc left; it makes no difference whether the object be cleaned mechanically or chemically. Two preparations are requisite for the purpose of tinning. Zinc powder - the best is that prepared artificially by melting zinc and pouring it into an iron mortar. (See No. 3312 (To Granulate Zinc).) It can be easily pulverized immediately after solidification; it should be about as fine as writing sand. A solution of protochloride of tin, containing 5 to 10 per cent., to which as much pulverized cream of tartar must be added as will go on the point of a knife.

The object to be tinned is moistened with the tin solution, after which it is rubbed hard with the zinc powder. The tinning appears at once. The tin salt is decomposed by the zinc, metallic tin being deposited. When the object tinned is polished brass or copper, it appears as beautiful as if silvered, and retains its lustre for a long time. This method may be used in a laboratory to preserve iron, steel, and copper apparatus from rust; and would become of great importance if the tinning could be made as thick as in the dry way, but this has not as yet been accomplished.