Thirty-one of the slides are produced by the Paget three-colour process which was devised by Geoffrey S. Whitfield in 1912. This was a screen process using collodion-coated plates which were coloured at various stages during production. The plates were placed on the market in 1913 but were discontinued in the early 1920s as the price of screens became too high after WWI. Brian Coe states in his book Colour Photography that "the Paget Printing Process was one of the very few additive colour printing processes to see any kind of use. Also included are three demonstration slides produced by Sanger Shepherd's process.