ABSTRACT
Even though an object may be reproduced in “true color” using digital or print media, experience shows that the reproduction still doesn’t look real. What is missing is the third dimension, in particular, on a microscopic scale. This third dimension, the roughness of an object surface, is what determines whether an object is glossy or matt. The surface roughness also provides microscopic shadowing effects which provide the viewer with a sense of texture as well as providing the human perception system with cues as to the subtleties of changes in the third dimension.
In industry, techniques for measuring and quantifying roughness have been used since the middle of the previous century. In this chapter, the introduction of such “objective” measurements into conservation science will be discussed and, as with color, juxtaposed with subjective judgments of appearance, in particular, of gloss and matteness. A number of techniques for roughness measurement will be introduced, including macroscopic tools based on raking light photography, to industrial and research grade profilometry down to almost atomic scales. Several case studies will be discussed, showing the usefulness of these techniques, but again questioning as to how much detail is really necessary for practical conservation work.
