This is recommended as being free from the defects of many of the other mordants, and as giving a clean vertical bite.
Several formulæ contain salts of copper.
Roret. | ||
|---|---|---|
| Nitric Acid | 62 | parts. |
| Distilled Water | 125 | parts. |
| Alcohol | 187 | parts. |
| Nitrate of Copper | 8 | parts. |
Iodine is recommended as a very efficient mordant for steel, being free from the inconveniences caused by the disengagement of gas, as when biting with nitric acid. Messrs. Schwarz and Boehme give the following:
| Iodine | 2 | parts. |
| Iodide of Potassium | 5 | parts. |
| Water | 40 | parts. |
This may be further diluted up to 40 parts more water, for etching the finest lines. It gives good deep lines, sharp, and with clear edges even, for the finest and closely ruled lines have no tendency to run one into the other.
The following resembles the etching fluids for copper, commonly known as “Dutch mordant.”
Cooley. | |||
|---|---|---|---|
| Hydrochloric Acid | 5 | parts. | |
| Water | 95 | parts. | |
Mix and add: | |||
| Chlorate of Potash | 1 | part. | |
| Water | 50 | parts. | |