| Bay Salt | 2 | parts. |
| Sal Ammoniac | 1 | parts. |
| Verdigris | 1 | part. |
These are pounded together, and the mixture kept in a bottle. {114}
When required for use, grind up a little in a glass with some syrup of old honey, so as to make a mixture which flows readily. It may be used with a brush like a color. It is used after the bitings of aquatint plates with acid, to give finish and vary the tints.
Fielding (for aquatint). | ||
|---|---|---|
| Nitrous Acid | 1 | part. |
| Water | 5 | parts. |
For the strongest touches, nitrous acid and water, equal parts, applied with a feather or brush. No. 19 may also be used for this purpose, either with or without a little gum.
Hamman.
| Distilled Water | 12 | parts. |
| Alcohol | 3 | parts. |
This is said to give a grain in biting, so that the ordinary grained ground may be dispensed with.
Electric Etching.
It has frequently been proposed to etch by means of electricity, and in some cases it may be an advantage to do so.