The etching solution made by the following formula has an advantage over other etching solutions in that it will not rust the most highly polished steel, and it is not in any way injurious to the hands or clothing - as a matter of fact the hands can be dipped into it with no ill effects. Mix 6 ounces distilled water; 4 ounces sulphate of copper, 4 ounces chloride of sodium (common salt); 1 dram sulphate of zinc; ½ dram sulphate of alum. The solution is applied in the following manner: The piece to be marked is covered with melted beeswax, and the inscription to be etched is marked through the wax with a fine pointed tool, leaving the wax undisturbed save where the marking is to appear. The markings are then filled with the fluid and allowed to stand for three hours. The result will be a very sharp and distinct lettering.
Philadelphia, Pa. L. Meyers.
Stamping tools with steel stamps will spring them and throw them out of true. Machinists should write their names on their steel tools using a fluid made of nitric acid 1 part, water 2 parts. Heat the tool gently until some wax that has been put on it melts and spreads thinly over the surface. When cold blacken the wax at a candle; then write on the wax with a steel point deep enough to touch the metal, and cover the writing with the fluid. In about three minutes wash and remove the wax. This fluid, however, will spread more or less and the writing will not be very fine. A better fluid can be made thus: Alcohol 2 parts, nitric acid 1 part, distilled water 15 parts, and nitrate of silver ½ dram per quart of fluid. Nitric acid, however, produces vapors that are disagreeable and harmful. Chromic acid made by dissolving one part of bichromate of potash in 5 parts of sulphuric acid, for this reason is more desirable as an etching fluid, although much slower in its action. J. M. Menegus.
Los Angeles, Cal.
First heat an iron or an old pillar file with a smooth side, and with it spread a thin, even coat of beeswax over the brightened surface to be etched. With a sharp lead pencil (which is very much preferable to a scriber) write or mark as wanted through the wax so as to be sure to strike the steel surface. Then daub on with a stick some etching acid made as follows: 3 parts nitric acid; 1 part muriatic acid. If a lead pencil has been used the acid will begin to bubble immediately. Two or three minutes of the bubbling or foaming will be sufficient for marking, then soak up the acid with a small piece of blotting paper and remove the beeswax with a piece of waste wet with benzine, and if the piece be small enough dip it into a saturated solution of sal soda, or if the piece be large swab over it with a piece of waste. This neutralizes the remaining acid and prevents rusting, which oil will not do.
If it is desired to coat the piece with beeswax without heating it, dissolve pure beeswax in benzine until of the consistency of thick cream and pour on to the steel and spread it evenly by rocking or blowing, and lay it aside to harden; then use the lead pencil, etc., as before. This method will take longer. Keep work away from the fire or an open flame. A. S. Gun.
For acid resisting ground use a mixture of 2 ounces white wax to which when melted is added 1 ounce gum mastic in powdered form, a little at a time, until the wax and gum are well mixed. Then, in the same way, add 1 ounce powdered bitumen. When this is thoroughly mixed add to it ½ of its volume of essential oil of lavender. This should be well mixed and allowed to cool. The paste can be applied with a hand roller, and if it is too thick, can be made to flow easier by adding a little more oil. When the paste is applied to the copper plate, expose it to a gentle heat in order to expel the oil of lavender. For a biting or etching acid use a mixture of 5 parts of hydrochloric acid, 1 part of chlorate of potash and 44 parts of water. The water is heated and the potash added. The acid is added first when the potash is fully dissolved. This mixture is used by immersing the whole object to be etched, the object, of course, first being covered on all sides by the acid resisting ground. Oliver E. Voris.