The sessile drop technique is used in CREST for contact angle determination and surface energy of different coatings/materials. The contact angle of the coating is measured using an FTA-200 instrument. The contact angle is described as a quantitative measure of the wetting of a material by a known liquid. If the contact angle is below 90ᴼ, the material is wetting or hydrophilic; if it’s above 90ᴼ, the material is non-wetting or hydrophobic. The liquid used for such experiments is referred to as the probe liquid, water is usually used but other liquids can be used. The test is performed as specified in standards ASTM D7334-08, and ISO 19403-1:2017.