Printmaking: Intaglio: Acid Bath
The acid on metal process is called "bite"
For etching steel you would normally use Nitric acid. Copper works best with chloride acid and
zink can be used in Ferric Chloride or Nitric acid.
The acid must be diluted with water before it can be put in the acid bath. This is usually a flat wide plastic container which is also acid resistant.
The stronger the acid is, the faster and stronger the bite will be, and
the strength of bite will determine the effects that can be achieved.
The longer you keep the plate in the acid the stronger and deeper it will be etched.
(deeper lines and darker areas)
To increase the bite, a soft feather is used to remove the bubbles which surround the etched areas.
This process should be repeated every 10-15 minutes, depending on the strength of the acid.
For plates with softground,
the feather must be used very lightly to avoid creating any marks in the ground
When the biting is over, the plate can be cleaned with running water. (Whitespirits if any stopout is used)
Acid baths should only be maintained and managed by professional printmaking technicians in a printmaking workshop,
as acids can be very damaging to the skin as well as flammable. It should be handled with care.
Undiluted acid can burn right through the skin so printmakers should wear goggles and gloves at all times when using the acid bath.
The skin should also always be protected from solvents with barrier cream.
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