“Fogging “in plastic films refers to condensation of water vapor on the surface in the form of small discrete droplets, which results from differences in surface tension between the water droplet and the polymer surface. Fogging may occur as a result of either a drop in temperature on the inside surface of the film below the dew-point of the enclosed air/water vapor mixture (“cold fogging”), or by cooling of the air near the film to a temperature at which it can no longer retain all the water vapor; excess water condenses upon the film (“hot fogging”). In agricultural applications as greenhouses, fogging will affect the transmittance of light, cause’s burns of the crops by the lens effect of the droplets, and a continuous water drip. 

SIVA Antifog Additvie uses a proprietory blend of additives that migrate to sarface tension of the water droplets that many from. When the surface tension decrease, water beads tends to "wet out" meaning the contact angle is reduced. The reduced contact angle improved transparency and aesthetic qualities.