C-type printing

A positive is, obviously, the opposite of a negative – that is, it is an image which is not reversed. Positive images are made through a double negative: silver salts react to light producing a negative which, when projected onto photographic paper (more silver salts), produces a positive.

CMYK is an industry standard abbreviation for cyan, magenta, yellow and black. These are the colours used in standard four-colour printing (as in inkjet and Iris printers).

Also known as heliogravure, photogravure is arguably the finest photomechanical means of reproducing a photograph in large editions. Copper plates are acid-etched directly from an original silver print; the etched areas then hold differing amounts of ink in order to correspond to the tones of the original print. If prints remain untrimmed, the impression of…

Different types of photographic paper have varying degrees of susceptibility to fading over time. The main cause of this is exposure to UV (ultra violet) light, although humidity, temperature, pollution and acidity are all contributing factors. Exposure to direct sunlight should be avoided, and UV-resistant glass can be used when framing.

A particular type of reversal (R-type) colour paper and printing process which gives strong colours (often with striking reds) and creates a long-lasting print. Printing in this way from a positive image results in exactly the same colour saturation as the original, and greater contrast.

A sheet of transparent film coated with silver salts which react when exposed to light (usually in a camera). In black and white negatives, one layer of salts reacts to white light (the full spectrum of light). The result is a reversal of normal vision: the shadows are light, the highlights dark. In colour negatives…