HL particles at weight fractions varying from 15%, 30% to 45% were denoted as HL1, HL2 and HL3, respectively. Each mixture was casted on black and white chart paper (Captain coating company, Thailand) using a laboratory film applicator to obtain a wet thickness of 150 m. After drying at room temperature for 48 h, the ratio (%) of hiding power or contrast ratio of coating film on black to white chart paper was determined and analyzed using a reflectometer, a color guide (BYK Gardner). For each measurement, the reflectance of coating casted on black char twas set as zero and that on white chart area was evaluated. The average contrast ratio was obtained from four different positions over both black and white areas.