decreased in the product (Table 2). Although, chemical composition
of decomposed product changed by washing with different
H2SO4 solution (Table 2) there was no differences observed
in the XRD patterns (Fig. 2). This result can be explained by
ion exchanges between decomposed product and acid solution
without any variation in the structure.12
3.2. Production and characterisation of pigments
3.2.1. V–zircon blue pigments
In Table 3, L*a*b* values of glazes containing pigments
prepared with decomposed products and calcined at different
temperatures are given in comparison with that of an industrial
V–zircon pigment (CP) and pigment prepared with pure oxide
(VO). Pigment prepared with decomposed product washed with
water has no colour as given in Table 3. When decomposed productwashed
withH2SO4 solution, the colour of pigments visually
changes from white to blue. The −b* values that indicate blueness
increased when decomposed product washed with H2SO4
solution, while −b* decreases with increasing calcination temperatures.
The blue colours on the tiles containing pigments
prepared in this study are less intense in comparison to the industrial
pigment but is comparable with that colour exhibited when
the pigments prepared with pure oxide is used.