Photo-engraving, Photo-etching and Photo-lithography in Line and Half-tone / Also Collotype and Heliotype

by W. T. Wilkinson

As soon as the zinc plate begins to get hot, there will be a tendency to curl slightly away from the hot plate, which, if allowed, would prevent the ink being evenly melted. To prevent this, take a brad-awl in each hand, and press down the sides of the zinc, taking care not to touch any of the picture.

Allow the zinc to remain on the hot plate until the ink and resin are melted and run down to the bottom of the etching, then remove it and lay it on the cold slab until the plate is cold.

When cold, smear the plate with the gum solution, fan it dry (never use heat for drying the gum), moisten with wet sponge, roll up again (use the leather roller), using the ink pretty stiff on the inking slab; keep the surface of the zinc well moistened. When the roller gets too much water upon it, pass a piece of damp cheese-cloth over it to remove the water; then roll the roller vigorously on the slab until it again bites the ink. Continue rolling the zinc until all portions have received due attention from the roller. N. B.—Some of the closest work will be quite blocked up this time, and each subsequent rolling will block up more and more, until only the very open work will be left.

Now allow the zinc to get dry, then cover it with resin, brushing from all sides, so as to coat the sides of the lines as well as the top, and then remove all superfluous resin from the whites with a damp sponge. The zinc is now ready for the next etching, for which more acid is added to the solution in the etching tray.

Rock the tray carefully, watching the zinc to see that the acid is neither too weak nor too strong, until the progress can be seen by examining the plate; the time, with the proper quantity of acid, is twenty to thirty minutes.

When the etching has proceeded far enough, after washing and sponging, again allow it to dry, then place it upon the hot plate until the ink is melted and runs down the sides of the lines; then cool, smear with gum, fan dry, moisten with sponge, and roll up as before; dry, cover with resin, using a {60} camel’s-hair brush, then dampen with a sponge and give a fourth etching, using the same precautions as to strength of acid and duration of rocking as before.

Now cool the plate; get a little more ink on the roller, and roll the plate whilst cold. When the surface of the lines has a nice even coat of ink upon each and all (coarse and fine), again warm the zinc on the hot plate until it is just too hot to hold in the fingers; then cool it again, varnish the back with shellac varnish, then make a mark with a blunt point, in the ink on the margin, so as to lay a short line of zinc bare to the action of the acid.

The round of operations is repeated; but for rolling up for the fifth and subsequent etching, a flannel roller is used, and more ink will be required upon the slab; it will also require to be a little thinner.

For some subjects six or seven etchings will be required, whilst for others—especially where there are whites that are too small for cutting out with a fret saw or router—ten or twelve etches will be required. Practice, the best teacher, will soon enable the operator to judge how many are required.

The etching having been carried as deep as is judged sufficient, sprinkle the plate liberally with turpentine, and with a stiff scrubbing brush loosen the ink from the lines, and wash it off with a solution of American potash.