Spreading Behaviour of Silicone Oil and Glycerol Drops on Coated Papers

The effect of physical properties represented by viscosity and surface tension of liquid spreading on coated papers was investigated. Two substrates of different surface roughness were used to study the spreading behaviour of silicon oil and glycerine/water solutions in terms of contact angle, wetted drop base area and drop height as a function of time. The liquid spreading on coated papers was found to vary depending on the liquid physical properties. Liquids with lower surface tension (silicon oil) and viscosity prevailed better wettability and vice versa. High surface roughness reduced the liquid spreading. Despite being traditionally used as a wetting indicator, contact angles were found to be insufficient to evaluate the spreading of liquids on these substrates. Hence, other parameters such as drop base area and drop height should also be considered.