After the transfer is made, the plate is etched with one of the foregoing preparations, then inked in and dusted with finely powdered resin, which adheres only to the lines. This procedure is followed after every biting, the plate being warmed to melt the resin and inky coating, so that it may run down between the lines and protect them from the undercutting action of the acid.
Kruger, in his Die Zinkogravure, recommends for the first relief etching, nitric acid 30 to 40 drops to 100 grammes of water, applied for five minutes. For each subsequent etching, 8 to 10 drops of acid are added for each 100 grammes of water, and the time is increased, from five to fifteen minutes. For the final etching of the broad lights he uses:
| Muriatic Acid | 4 | parts. |
| Nitric acid | 1 | part. |
| Water | 16 | parts. |
To soften down the ridges between the lines the plate is inked and dusted as before, and etched with dilute nitric acid at five per cent., applied for a {117} minute, and the inking, dusting, and etching repeated as often as may be necessary.
THE DIFFERENCE.
Finally, in this department, only the novice will require an explanation of the varied productions possible by means of the processes already given. As actual examples, reference may be had to the illustrations in this work. Figures 1, 2, and 3 are specimens of line work, zinc etchings made from pen and ink drawings. The figures in the following chapter were made in the same way.
Fig. 13.
Fig. 14.