In this method (1-3), the contact angle between air and liquid on a paper surface is taken as a measure of the resistance of the paper surface to wetting by the liquid.
The initial angle of contact or initial wettability is considered to be a measure of the ruling quality of the paper. The rate of change in the wettability is considered to be a measure of the writing quality.
There are other important purposes for which surface wettability of a paper by contact angle measurement may be of interest, for example, with regard to adhesives. However, considerable modification of the procedure might be required. Hence, this procedure is restricted to ruling and writing purposes.
