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We surveyed eighty-nine Japanese woodblock prints testing all the colors on each object. Analysis of the data showed trends in color stability, colorants used, colorant concentration, and preservation quality. To gauge the extent of color change, micro-fading tests were also performed on blue wool standards 1-3 (BW1-3) as a way of classifying the level of stability. Colors that fall into this range of fading are considered light sensitive. Most of the colors tested showed fading rates between BW2 and BW3 although some were more stable (i.e. faded slower than BW3) and others were slightly more fugitive (i.e. faded faster than BW2). The overall trend for fading for the different colors was as follows: yellow>green>purple>red>blue, with a few exceptions on some of the prints. The green and purple colors tended to be a mixture of either yellow and blue or red and blue respectively. The more fugitive yellow and red colorants tended to fade more rapidly leaving behind the relatively stable blue. We were also able to identify dayflower blue, indigo, Prussian blue, safflower red and lac or madder lakes (the latter two being nearly indistinguishable) by their unique reflectance spectrum. Often the colorants on the prints were applied at different concentrations to provide contrast and depth to the object. We tested the different colorant concentrations on the prints and found that the medium depth of shade was more light sensitive than either the pale or dark shades. This is consistent with the behavior found for paint glazes at different concentrations. Further, micro-fading results provide insight into how prior fading on a print will affect its further fading. Results were compared between prints with poorly preserved versus well preserved color and areas of approximately the same color were found to have essentially the same light sensitivity regardless of their prior fading. For more information: |
The
colorants used to create Japanese woodblock prints are considered to be highly
sensitive to light exposure. Through a collaboration with both the
Carnegie Museum of Art and the Library of Congress, we are testing a large
number of 18th- and 19th-century Japanese woodblock prints from their collections
to determine if our current understanding of the light-sensitivity of these
prints is correct or if our assumptions and therefore preservation guidelines
need to be altered.