Continuous Tone Colour Printing in Two and a Half Dimensions Through a Combination of 19<sup>th</sup> Century Analogue Methodologies and 3D Printing

Abstract

This paper proposes a contemporary method of continuous tone colour printing based upon the Nineteenth Century printing process of Woodburytype as developed by Walter Bentley Woodbury in 1865. Woodburytype was the only truly continuous tone printing process yet invented, and died out in the late nineteenth century as more expedient and cost effective methods of printing prevailed, thus laying the path for current CMYK print technologies. Digital print itself, since its development as a range of colour printing technologies, has followed a route based on the half-tone dot and four colour separation predicated around CMYK. In recent years stochastic algorithms and dithering have allowed the lay down of multiple passes and colour sets to create a near continuous tone image. The downside of this approach is that in order to create a full colour subtractive image, the resultant prints have very little surface topography and a mechanical uniformity that demonstrates none of the surface characteristics, tactile qualities and rich tonal warmth of the 19th century photomechanical processes.Current research at the Centre for Fine Print Research (CFPR) at the University of the West of England, Bristol, is exploring the potential of CNC milled imagery, where the tonal range of each colour is assigned a physical height to produce a continuous tone topographic relief printing matrix, from which the colour image is cast in a silicone ink. A translucent image is cast from each of the colour matrices and each colour is assembled one on top of another resulting in a true four colour separation continuous tone print, where colour tone is created by physical depth of colour.