pigmented colorants: dependence on media and time - Cornell ...

too brittle and cracking. While working with pigments, slightly more water can
be added as needed.
5.1.4 Substrate
The magnitude of the number of samples demanded that the substrate to which
paint was applied had to be easy to make and provide a consistent surface. The
device used to measure the diffuse reflectance governed the size of the sample.
The samples needed to be circular with a diameter of 19mm to reasonably fit
in the measuring device. In order to provide enough space on each sample for
both priming and painting, each sample was made to be approximately 31mm in
diameter.
The samples needed to be sturdy and suitable for many drastically different
types of binding media. Canvas or paper are too flexible of supports to be used in
conjunction with brittle binders (Casein, for instance, would be very susceptible
to cracking on such supports). Also, it is important that the support for all of the
samples in the research be consistent, as different supports for different media may
introduce unwanted errors. Therefore, the work demanded rigid supports.
Mounted canvas was chosen for the surface characteristics of canvas, as well
as ease of operation. The canvas selected was the inexpensive, readily available,
cotton duct fabric. A template for the desired shape and size was made, and the
canvas is easily cut with scissors. The backing also needed to be easy to cut rapidly.
Quarter-inch Fome-Cor board was chosen for this purpose. It is a polystyrene
core bonded between high-quality papers to provide a lightweight, rigid, smooth
surface. It resists warping (though on this scale, this is not much of a concern)
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and is easily cut with the sharp blade of an X-acto TM knife on a cutting mat. Each