A technical dictionary of printmaking, André Béguin. EN

Adhesive materials

1. SHEET AND STRIP ADHESIVE MATERIALS.
These are usually found in rolls of varying size and are made of different substances. Scotch tape or transparent cellulose tape which is in everyday use (in offices, for example) can be used for various tasks in silkscreening (as for example making the borders of the screen in manual silkscreening. The width readily available range anywhere from l2mm (about half an inch) to 3Omm (about 11/4 inches) while the length of such tape may be as much as 60 metres (about 200 ft). This tape is also available with both sides being sticky. Maskinq tape, on the other hand, is made of slightly creped paper. It is also used in silkscreening to protect certain parts of the screen even though it adheres somewhat less well than scotch tape and is particularly sensitive to humidity. Masking tape is usually used for a rapid and provisional preparation of the screen before the inking is done but it can also be used to stop-out, to protect the screen margins after it has been streched and fixed to the frame, and to fix small tears. Masking tape is also available with two sticky sides. Insofar as concerns the sizes available it comes in rolls ranqinQ from l2mm wide (9 or 13 mm for the two sticky sides) up to 50 mm wide (about 2 inches). The maximum length available is about 60 meters.
Adhesive plastic sheets (contact paper) can be used to protect metal plates during biting either by sticking whole sheets onto the back of the plate or by cutting out shapes and sticking them onto the side to be bitten. Strips of acetate can be used to make or fix pans*.
Tape that is sticky on both sides can be used to fix two objects to each other. Essentialy such tape is used in technical engraving to compose texts that are not rectilinear. The characters are glued on and used as a model for pantographic work [* machine ( engraving machine ) ].
Adhesive cloth for simple book binding and for packaging is also available. In photographic work, when certain parts of the picture must be hidden, a special black and opaque adhesive is used (6 mm wide and 60 meters long).
In silkscreening, when using the stencil* system, artists use sheets that are stuck onto the screen by means of a layer of adhesive varnish.

2. ADHESIVE LETTERS, SIGNS AND NUMBERS.
At present a fairly large range of letters, numbers, signs, symbols, ruled screens, and lines are available in the form of transfers. Although primarily used for drawing they can also be used in print making. In silkscreening they can be used to compose texts or illustrations since these transfer adhesives can be glued right on the screen. Printing can be done in two distinct ways. The first way is to apply ink to the screen on which the transfers have already been placed. In this case the transfers will stop out the ink and, after printing, the signs and symbols will he the same colour as the paper used for printing. This method is only compatible with a water base ink* and for a limited amount of printings because the transfers are not only dissolved by oil base and cellulose base inks but also deteriorate after some sixty passages of the squeegee (one hundred if done carefully). The second method is to fix the transfers onto the screen and then proceed to spread a layer of filling* so that the layer be quite thin. The tranfer may be dissolved once the filling has completely dried. This is done by applying turpentine on both sides of the screen. Be sure to thoroughly wet the places where the transfer sticks to the screen so that it will come off in pieces. The filler used must, of course, be insensitive to the turpentine used. In fact, it is a good idea to use a water-based filler which will permit the use of acetone to dissolve the tranfer. By this means empty spaces will appear in the form of the transfers that have been removed while the rest of the screen will be filled. In short, the latter method is the exact reverse of the former one. It may be added that the latter method will also work with oil and cellulose based inks if the filler used is waterbased. It also presents the advantage of allowing a large number of printings without problems cropping up. Above all it allows for black texts on a white background since the screen used for printing need not be reversed as compared to the printed surface whereas it is always reversed in other printing methods. In fact, any kind of sign can be used except for letters and numbers, in which case a transparent composition must be made and then photographically reversed [* transfer ]. It must be pointed out, however, that this system gives good results (good definition) only with relatively large characters as the smaller ones are rarely properly preserved. On the other hand, the photographic procedure mentioned above gives good results even with small letters whose definition remains good.

3. ADHESIVE VARNISH.
In silkscreening and for certain other uses (for example to put an adhesive coat unto a decal) one may use an adhesive varnish which at times is simply refered to as a varnish. There is a specially treated paper which protects such a varnish.