To tin cast-iron articles, dissolve chloride of tin in water until the solution is fully saturated; this saturated solution is to be thinned down when needed for use, by ten times its volume of water. The articles which are to be tinned are to be wrapped around lightly with zinc sheet or wire and left in the solution ten to fifteen minutes. On removing the articles they are to be dried in sawdust, after washing well with clean water and brushing them with a wire brush, and then polished with prepared chalk. Robert Grimshaw.
Having occasion to darken, polished spots on case-hardened parts in order to make the entire pieces appear uniform, I immersed them for about 20 seconds in a solution made as follows: Eight cubic centimeters of nitric acid and 40 cubic centimeters of water, same being measured by a druggist. The pieces I refer to were case-hardened in the usual manner (packed in bone dust). After immersing as above stated, rinse off in clear running water and you will not be able to distinguish the difference between the part which was formerly bright and the dark portion. Harry Ash.
Mix whiting and white lead with boiled linseed oil to a thick paste: add some japan dryer, and thin with benzine or gasoline. This makes a fine preparation for whitening sheet iron and other work previous to laying out, as any lines drawn on the surface show up very distinctly. It also makes a very good stenciling or marking paint. A. D. Knauel.
For laying out work on structural iron or castings a better way than chalking the surface is to mix whiting with benzine or gasoline to the consistency of paint, and then paint it with a brush; in a few minutes the benzine or gasoline will evaporate, leaving a white surface ready to scribe lines on. Albert D. Knauel.
Occasionally it becomes necessary to darken polished or ground parts to imitate case-hardening; in order to accomplish this result use this mixture: 1 part nitric acid and 20 parts water. Immerse the article to be treated about 20 seconds, then rinse with clear water. A splendid result can be accomplished by following the above instructions. Harry Ash.
To tin by cold process finished work In iron, brass, or steel such as pins, tacks, wire goods, etc., put twenty pounds of stock well cleaned in sawdust, in a deep pan (14x20x 3 inches is a good size) having a false bottom of zinc. Heat to the boiling point a mixture of ¼ ounce of sulphuric acid and 2 ounces of tin crystals (stannous chloride) and pour over the work. Let it stand ten minutes and then stir well, using a rake, and then let it remain ten minutes longer. Repeat the process and if two coats are not enough, give it a third coat. The zinc bottom must be washed twice a day, as rusty or oily work will not tin satisfactorily.
To polish the work, put in a wooden tumbling barrel and pour in a water pail full of strong soap and water. Let it tumble fifteen or twenty minutes, according to the nature of the work, and then tumble for a few minutes in hot sawdust to dry it. J. L. Lucas. Bridgeport, Conn.
To make a non-reflecting or mat surface on small steel articles such as screws, small steel stampings, etc., which at the same time shall be perfectly rust-proof, proceed as follows: Mix 2 ounces of powdered tartar with 20 ounces of water. Put the articles to be treated into this mixture in an earthen pot, and boil until they become yellow. Then place the articles in a tray with a solution of sulphate of copper (blue vitriol); take out when copperized and put in a tray with sulphur-ammoniac. When black, take out and rinse off with water. After the rinsing has been done carefully, mix a quantity of clean, very dry, beech-wood sawdust with sufficient sweet oil, to render it slightly oily. Then thoroughly mix and rub in some powdered graphite, but only enough graphite should be added to give the whole a blackish appearance. Throw into the sawdust the steel parts to be blackened, but not more at a time than about one-third of the quantity of the mixture. Put the whole in a small coffee roaster such as is used in private houses, and after shaking well, roast the contents over a gentle flame, in constant motion, until the sawdust is burned to charcoal. The parts are then ready to be taken out and cooled. The roaster should be tightly closed during the roasting operation.
It is not necessary to lacquer the parts as the color put on in this manner will not wear off by ordinary handling. The parts will have a nice mat surface suitable for articles used in photographic manufacture and art goods. The formula used was a secret for many years and was successfully used by the inventor. Max J. Oches.