Woodburytype, invented by Walter B. Woodbury and patented in 1863, was the first commercially successful mechanical printing process for the permanent reproduction of photographic quality pictures and today is still unsurpassed in producing continuous tone images of the highest quality. Woodburytype was made commercially obsolete by the introduction of Halftone to the printing industry which allows the printing of text and images at the same time and does not require the complex production methods or the time-consuming trimming and tipping-in of the images.
In Woodburytype contrast and greyscale are generated by a relief of pigmented gelatine. In contrast to traditional printing methods where the ink is driven into the paper by pressure, the gelatine layer sits on top of the paper surface. The pressure of the printing press has to be carefully tuned to achieve a reliable release from the printing plate without chasing the ink into the substrate. Substrate surface chemistry and paper porosity are parameters which have to be controlled for a successful release and these also influence contrast and greyscale in the printed image.
Present day Woodburytype practitioners use photographic paper avoiding paper treatment described in some historical recipes. The grades used have a completely sealed surface which does not allow air trapped between plate and paper to escape, generating air bubbles in the final print. Historic documents show that in the 19th century commercial print companies, Goupil for example, were producing several thousand prints per day. This is in stark contrast to today’s very low success rate, with yields reported between 15 to 20%.
In our research we use an Albion platen press as our printing platform, where pressure is controlled by adjusting the packing within the press. The pressure is quantified using compression load cells. A range of different papers, supplied by St. Cuthbert’s Mill and John Purcell Paper, were tested for their suitability for the process. Contrast and greyscale were recorded as a function of the degree of absorption of the ink by the paper and as a function of compatibility of ink and surface chemistry. Contrast and greyscale are objectively determined by measuring optical density with the Konica Minolta Spectrodensitometer FD-7/FD-5 mounted on the ColorScout A+. Correlating optical density with the actual parameters of the printing process will allow the user to choose an image appearance suited to the image content and desired artistic expression.
Applying the gelatine layers via ink jet allows the addition of active layers like liquid crystal layers. We will report first results.
Klein, S., & Leech, D. (2019, April). And now for something completely different: Woodburytype. Presented at British Liquid Crystal Society 2019 Annual Conference, Leeds, England