User's instructions for Badger Aquatint Solution.
We use an acrylic resist as aquatint. When using acrylic grounds, it is generally important to observe the correct proportions and mix the ingredients well according to the manufacturer's instructions.
To apply the aquatint, we need an airbrush and a compressor. Although the product is non toxic, it cannot be healthy to breathe in the tiny ink particles that spray from the airbrush. We recommend wearing a dust mask and installing a cooking canopy or some other form of exhaust system in the aquatint cabinet (see page 85.)
The aquatint is applied to the plate by spraying it on with an airbrush. This tool provides a wide range of possibilities for creating different gray tones in a single etching. The airbrush can provide a uniform destribution of the sprayed resist as in a traditional aquatint. Alternatively it can be applied as lines, areas of different densities, splattters, isolated clouds etc. In short, the airbrush works by air pressure and functions like a spray gun.
Applying the Aquatint
Run some water though the airbrush to make sure that it is clean before screwing on the glass containing the aquatint. An airbrush must always be very thoroughly cleaned, as it will otherwise clog up easily. Rinse it with clean water after every time you use it. If it does clog up, make a mild solution of soda and water and run that though. When the obstruction has dissolved, run some clean water through it again before use. Place the copper plate almost vertically against a piece of white paper. Fill the glass container under the airbrush with the aquatint ground. The density of the aquatint grains is determined by the amount of air that is admitted into the etching ground. Adjustments are made partly by loosening or tightening the valve of the spray gun and partly by changing the distance between the gun and the plate. It may be difficult to see the grains on the copper plate, which is why it is important to place it against a white background sheet. This will show the position and quality of the aquatint grains.
You achieve the finest aquatint by adjusting the airbrush to admit the highest possible amount of air in proportion to the etching ground. As in all other aspects of life, practice makes perfect; therefore training sessions on paper or cardboard are very useful. I recommend starting with the exercises described in the instructions on how to use the airbrush. If you want a coarser aquatint, adjust the airbrush to admit less air, and increase the distance from the plate. We now describe the difference between a uniform aquatint and a modulated aquatint.
The aim here is to spray a fine, mist onto the plate, not to cover it completely. Hold the brush at arm's length and spray the copper plate evenly, going beyond the edges of the plate to avoid irregularities. Use smooth, even movements in parallel lines across the plate from left to right and right to left, moving simultaneously down towards the bottom of the plate. Try the technique on a piece of white cardboard first for practice, until you are able to see the aquatint as an even misty distribution of fine dots on the cardboard. Then attempt the technique on the cleaned, de-greased copper plate, but keep a piece of white paper behind the plate to show you what you are doing. If you make a mistake, simply wash off the aquatint immediately in cold water, dry the plate and try again.
After application, dry the aquatint for 20 minutes in the drying cabinet and etch it as you would a conventional aquatint. It is possible to take the plate out of the ferric chloride at any time and rinse, dry, inspect and stop out again. Just remember to de-oxidize the copper plates before stopping out, as the stop-out varnish will otherwise not adhere properly (see de-oxidizing, page 49). You can create sharp outlines within the composition by using masks and stencils made of paper or card. The outlines may in turn become basis for other techniques - such as transferring a fragment from a photographic image using photopolymer film.
The technique of spraying a modulated aquatint is not that different from that from a uniform aquatint. The aim is of course different - what is wanted in this case is not an even coating, but the creative use of the airbrush which enables the artist to produce areas of varying density, as in an airbrush painting.
The modulated aquatint is effective for creating spatial effects in abstract composition, for emphasising the weight of three-dimensional objects, and for many other purposes requiring tonal variation. Compared to a conventional aquatint, which has very sharp edges made by stopping-out areas on the plate, this method makes it easier to achieve a gradual transition from one tone to another.
As always, the most densly coated areas produce the lightest tones in the final print and vice versa. The experienced aquatint sprayer' thus does not need to etch, stop out, etch, stop out, etch etc., but you can of course spray the aquatint on evenly as described above, and use the stop-out in the traditional way if you feel more comfortable with that. Remember to de-oxidize before every coat of stop-out
Any area of the plate that has not been sprayed will naturally etch as an open bite. If you wish to avoid this, begin by spraying a thin coat onto the whole plate before commencing the actual composition.
Spit Bite Technique
The aquatint-sprayed copper plate may form the basis for the most beautiful washings - which are the intaglio version of watercolour painting. The effect can be achieved in many different ways:
If you do not de-oxidize the plate after each etch before applying a new etching ground or stop-out, the ferric oxide generated on the surface of the plate will cause the etching ground or stop-out to loosen and break up during the ensuing etching process.
De-oxidize the plate, paint on a thin coat of Acrylic Stop-Out Varnish and dry the plate in a drying cabinet for 5 minutes.
Removing the Aquatint and Stop-Out
Acrylic etching grounds are removable in a solution of washing soda in water. If you have applied more layers of aquatint it might be nessesary to use Caustic Soda if time is short. Etching grounds from the brand Lascaux alone cannot be removed in this solution. These can only be removed with Mystrol or Lascaux Remover.
source: Handbook of Non-Toxic Intaglio, Henrik Boegh