Details of sample preparation and applications for the source and special clays were presented previously (Doğan et al. 2006).
To determine the color properties of the
materials, L*
, a*
, and b*
values and whiteness index (WI)
were measured under the standard illuminant D65 by
using the CIELAB system (CM-700d Konica Minolta
Series Spectrophotometer). The spectrophotometer was
calibrated to the perfect white diffuser by a ceramic plate
with tristimulus values X = 90.3, Y = 92.1, Z = 105.7 and
chromaticity coordinates x = 0.3135, y = 0.3196. The pH,
water soluble substance, acid-soluble carbonate, and acidsoluble
iron of the samples were determined according to
the Turkish Standards adapted to European Norms TS EN
ISO 3262-10 and other Turkish Standards TS 2973 and TS
10521.