Ceramic application of mica titania pearlescent pigments

Mica based pearlescent pigments are widely applied in plastics, cosmetics, automobiles coatings among others, but they seem not explored by the ceramic industry. In this work, the potential of two commercial special effect pigments (with gold and silver lustre respectively) in the decoration of ceramic tiles was appraised by testing them dispersed into several ceramic coatings fired in a wide range of temperatures (700-1150?C). The pigments were characterized by XRD, FTIR, SEM, XRF and PSD, while their technological behavior was assessed determining phase composition (XRD) and colorimetric parameters (DRS) of ceramic materials, including a pearlescence index. Results indicate that titania mica pigments are stable into glassy coatings up to 900?C, being any deterioration of their optical properties due to anatase-to-rutile and muscovite-to-feldspar transformations occurring at higher temperatures or after long firing times. The pigment type with a gold shine is particularly suitable for third fire decoration of ceramic tiles, involving low temperatures and fast firing schedules, where it can replace expensive precious metals lustres. Moreover, a certain satin effect was appreciable in porcelain stoneware tiles, unexpectedly persistant after firing at 1200?