Abstract The ability of a PVC plastisol to liberate entrapped air during mixing and processing is an important factor to the processors. This property, known as air release, is affected by several variables such as resin, plastisol viscosity, surface tension, surfactant system and plasticizer type. A study was conducted to obtain a more fundamental understanding of the effects of these variables on air release. Complicating the accurate study of a plastisol's air release properties is the fact that current test procedures such as the vacuum rise, syringe test and Huff or ring test each have limitations imposed by either plastisol properties or by testing technique. Any one of these procedures alone may not adequately measure air release. This paper, in addition to studying the factors affecting air release, discusses these testing limitations and makes recommendations as to the best methods for evaluating air release properties in the laboratory.