Understanding pyrography, the photochemistry of 'scorched' decoration.

This paper examines the discolouration of pyrography artwork applied to three different wood species when exposed to natural light. Samples were 'scorched' in a controlled manner at a range of temperatures to produce different shades from light to dark. This allowed comparisons to be made between different wood species and different temperatures. It was elucidated that pyrography is the result of several processes developed between migrating extractive substances and coloured reaction products formed through the thermal degradation of wood components, which combine in caramelisation and Maillard reactions. Each species was shown to react differently. The results confirm that these colours, caused through the 'scorching' process, are extremely sensitive during light exposure. Light induced colour change was more profound for segments 'scorched' at 350ºC, particularly for the hardwood species. Overall, samples made of Douglas fir were found to discolour the least during exposure to natural light