tint strength 28 75 and contrast ratio 0 75 one skilled the art would appreciate that while the contrast ratio increase is small a mere increase of 0 40 will show a noticeable visual improvement in hiding power in this study the concentration range of nano zno u02dc 60 nm particle size was examined in paint a the concentrations of nano zno examined were 0 05 0 10 0 25 0 50 1 00 1 50 2 50 and 5 00 table 3 shows the tint strength and contrast ratio data for increasing the nano zno concentration in paint a the concentration of nano zno is expressed as a percentage based on total formula weight the data in table 3 illustrate that as the concentration of nano zno particle size of 60 nm is increased in the base paint a 0 05 5 00 the tint strength and contrast ratio increase as opposed to paint a without nanopigmentation the optimum use level of nano zno particle size u02dc 60 nm is 0 50 yielding a tint strength increase of 28 75 and a contrast ratio of 0 75 this study examines the effect of blending nanoparticles of different composition and different particle sizes into a typical base paint formulation paint b in this case the nanoparticles studied were zno u02dc 60 nm and u02dc 120 nm particle size and al 2 o 3 u02dc 50 nm particle size.