Etching-ground. A recipe for a cheap and yet a very good ordinary ground has been given on [p. xv]. The transparent ground consists of
| 5 | parts, | by weight, of | white wax. |
| 3 | „ | „ | gum-mastic. |
Gum-mastic costs about thirty-five cents an ounce. Melt the wax first, and add the gum-mastic in powder gradually, stirring all the while with a clean glass or metal rod.
Stopping-out varnish. (See [p. xvi.]) There is a varnish sold at painters' supply-stores under the name of “Asphaltum Varnish for Sign-Writers' Use,” which does very well. In Boston Asahel Wheeler sells it at fifteen cents a bottle.
Needle-holders are unnecessary if the points described on [p. xvi] are used.
Burnishers are sold at the hardware-stores, or by dealers in watchmakers' materials. They ought not to cost above fifty cents apiece.
Scrapers. Same as burnishers. Price not above $1. Some dealers ask $2, which is exorbitant.
A lens can be obtained of any optician. In Boston they can also be had of A.J. Wilkinson & Co., hardware dealers, 184 Washington St., at prices varying from $1 to $1.50.
India-rubber finger-gloves are unnecessary if you use the “plate-lifter” described on [p. xvii].
Nitric acid. Messrs. Powers & Weightman's “Nitric Acid, C. P.” (i. e. chemically pure), recommended on [p. xvii], is 42 degrees, and Messrs. P. & W. inform me that the strength is tolerably uniform. If you are an enthusiastic etcher it will be best to buy a seven-pound bottle, which is the next largest to the one-pound bottles.