ISO TS 14778:2021 "Paper and Cardboard - Determination of water contact angle by Optical inspection method" is a technical specification published by the international standards organization (ISO) that specifies procedures for the measurement of water contact angle on paper and Cardboard surfaces using Optical inspection method. The standard requires that the process of droplet formation, application to a planar substrate or measurement of the shape of droplets in contact with solids be performed by automated equipment. The limitation of measurement is determined by the function of the instrument used, which should be equipped with a digital image capture system of at least 50 frames per second and capable of performing the first measurement within 20 to 40 milliseconds of droplet contact with substrate. This method is suitable for most paper or Cardboard, but not for structured materials. By measuring the water contact angle, the surface wettability of paper and Cardboard can be evaluated, which in turn affects their printability, Spreader performance and surface preparation.