Surface free energy

Surface free energy is the established physical property governing how readily a liquid wets a surface and how strongly contaminants and organisms adhere to it — high-energy surfaces are easily wetted and bioreceptive; low-energy (hydrophobic) surfaces shed water and resist colonisation. In ATH it is a primary input to the Substrate Vulnerability Index (SVI = Σ(Mi×Wi)/N, where the Mi terms include surface free energy, capillary absorption, acid reactivity and Tg baseline), making a material's wettability a quantified driver of its colonisation risk and of which cleaning chemistry will work.