Acid-free

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).

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.

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 single image built up from several photographic prints.

Paper or material-based paper type used in printing black and white images from negatives (C-type). Available in all surface finishes, this thicker paper has a high-quality texture, gives an excellent finish, and adds ‘depth’ to the image through the faint weave of the paper/fibre.

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…