The aquatint spray cabinet is used to apply a grainy ground on to a plate by means of compressed air.
On top of the spray cabinet a fan and filter system have been built-in. The vapours that are released during spraying must be removed by this fan. The fan is equiped with a filter in order to stop the solid particles (varnish or acrylic particles) in the vapours. After some time the filter must be replaced. These filters are available in shops for kitchen equipment.
The fan must be connected to the outside air. The fan has two possibilities to connect the tubing. On the top side of the fan a connection point (diam. 10cm, 4") has been made as well as on the back side. The tubing should be made of 10 cm PVC. The connection directly from the fan to the tubing has to be made of a flexible material in order to avoid transmission of vibrations to the tube system.

The use of the spray cabinet is as follows:

• Switch the fan and lamp on.
• Make sure that the jet (air-brush) can be easily moved over the entire surface of the plate. However the plate is only placed in the cabinet after the testing of the grain on a sheet of paper in the back of the cabinet.
• The grain can be applied with either one or two different liquids: acrylic paint or varnish. Both must be fluid, well mixed, and have no sediment. The choice of liquid (either a varnish or an acrylic paint) depends on the granulation desired. The use of varnish gives a very fine and delicate grain. Preparing is simple indeed: filter a good quality liquid engraver's varnish and add to it about 1/3 turpentine in order to obtain a good fluidity. The acrylic paint solution is prepared by squeezing a tube of such paint into a container that can be closed hermetically. The paste is then diluted with water until fluid. The fluidity should, however, be just short of what is needed for an air-brush, that is to say a bit "creamy". On the market there are also ready made products available for this purpose.
• The jet should be used at a distance of 20 to 30 cm from the paper. The jet must be tried out on a piece of loose paper before using it on the plate. The grain size can be regulated by adjusting the nozzle. Make sure that the jet is quite homogeneous and continuous. The distance from the plate and the air pressure must also be checked. If the jet is too close to the plate it will splash, especially if it is a strong one. If the jet is too far away, the grain will get to the plate already half-dry and unevenly distributed. A middle pressure and a shorter distance are best when working on small plates. A strong jet and a greater distance are best for large format plates; insufficient pressure gives large and irregular drops. Excessive pressure sprays the grain in all directions.
• A pressure of 1,5 or 1,8 bar (1 bar = 1 kg/cm2) is usually appropriate if the liquid is thoroughly mixed. The nozzle opening should be tested on a loose piece of paper. A small opening will give a fine grain but it will take a long time to lay the ground. A big opening will produce a rougher grain but the work can be done more rapidly.
• If the quality of the grain on the paper is considered OK, the plate is placed in the back of the unit against the paper. It is best to start spraying again on the paper and to continue to spray on the plate without interruption. The reason for this is to avoid irregular spraying in the beginning. The same should be done during stopping.
• After graining the plate must dry, inside the Drying Cabinet, for a couple of hours. Leave the plate in the cabinet, turn off the fan and close the door. It is very important that no other dust particles attach to the plate during and after drying.