I have found the following receipt for a fluid for etching steel to be very satisfactory, both for frosting effect and deep etching. Mix 1 ounce sulphate of copper, ¼ ounce alum, ½ teaspoonful of salt (reduced to powder), with 1 gill of vinegar and 20 drops of nitric acid. This fluid can be used either for etching deeply or for frosting, according to the time it is allowed to act. The parts of the work which are not to be etched should be protected with beeswax or some similar substance. S. C.
The following solution will be found excellent and reliable either for very deep etching upon steel, or for the purpose of producing beautiful frosted effects upon the surface. Mix together 1 ounce sulphuric acid, ¼ ounce alum, ½ teaspoonful salt, ¼ pint acetic acid or vinegar, and 20 drops concentrated nitric acid. The etching effect produced by this solution depends upon the length of time it is allowed to act upon the metal. It is applied in the same way as ordinary etching acid.
Urbana, Ill. T. E. O'Donnell.
The various receipts for etching acid to be used on steel in most cases call for two-thirds muriatic acid. I find that the object of the muriatic acid is simply to remove the grease and foreign substance from the steel, and that if only enough muriatic acid is used to accomplish this purpose, the etching acid will work better and quicker. I have used etching acid with muriatic and nitric acids in almost all proportions and have found none so good as two-thirds nitric to one-third of muriatic acid. In some cases I have had good success even with a less proportion of the latter ingredient. Geo. W. Smith.
The following receipt for etching fluid for steel, was highly recommended to me, and I have tried it in comparison with another fluid on hardened steel. I found it will make very neat and sharply defined lines, and does the work very quickly:
Nitric acid, 60 parts; water, 120 parts; alcohol, 200 parts, and copper nitrate, 8 parts. Keep in a bottle having glass stopper. To use the fluid, cover the surface to be marked with a thin even coat of wax and mark the lines with a machinist's scriber. Wrap a bit of clean waste around the end of the scriber or a stick, and dipping same in the fluid, apply it to the marked surface. In a few minutes the wax may be scraped off, when fine lines will appear where the scriber marked the wax. The drippings from a lighted wax candle can be used for the coating, and this may be evenly spread with a knife heated in the candle flame. W. S. Leonard.
Soft Steel. - Nitric acid, 1 part; water, 4 parts.
Hard Steel. - Nitric acid, 2 parts; acetic acid, 1 part.
Deep Etching. - Hydrochloric acid, 10 parts; chlorate of potash, 2 parts; water, 88 parts.
Etching Bronze. - Nitric acid, 100 parts; muriatic acid, 5 parts.
Brass. - Nitric acid, 16 parts, water, 160 parts. Dissolve six parts potassium chlorate in 100 parts of water, then mix the two solutions and apply.
Where the name, initials, or monogram is etched on a tool, for instance a square blade, black asphaltum varnish makes the best "resist." Have a rubber stamp made with the design you wish to etch and stamp the tools with the same, using the varnish as you would ink on the stamp, the stamp having a fancy border around the outside edge. This method leaves the letters or design in relief and makes an unique appearance. E. W. Norton.