Characteristics of Lithography
In lithography images are always drawn on to the stones or plates using these materials that are either black or brown - requiring the drawing to be conceived in terms of tonality. Once the image has been processed however, the same drawing can then be inked in what ever colour is desirable. Inks used in lithography tend to be transparent and are thus capable of producing secondary colours during printing as each colour is layered usually from separate plates and stones.
Whilst some artists prefer to print only from stone, it is common nowadays for most colour printing to be achieved using either aluminium or zinc plates. These are plates that are specially manufactured, ball-grained with a surface that closely resembles that of stone. Being uniform in structure, lighter than stone and potentially large in scale, plates are ideal for experimenting with colour combinations; enabling changes in order and changes of colour during proofing. Often plates are printed in combination with stones, which may be used to print the final key image in black to help resolve the finished print.
Popular with many artists too are the photoplates that are ubiquitous in commercial printing or in offset lithography. These plates are manufactured with light sensitive emulsion and are designed principally for industrial use for the printing of both text and images on a massive scale. The catalogue, invitations and posters for this exhibition will all have been printed using some form of offset lithography, printed on an automated press and printed using either positive or negative photoplates.
Photoplates allow for a whole range of possibilities and an expansion beyond the purely autographic. Photoplates may be exposed with a wealth of material, including photographic and computer generated digital images, photocopies, as well as drawings that will have been prepared on translucent or transparent materials such as acetate, tracing paper or True Grain Film. The impressive print by Graham Flack Of Man and Angel printed at Edinburgh Print Workshop is one such image that was developed initially as a charcoal drawing on True Grain Film and which was then exposed on to positive working photoplates.