Typical factors influencing gypsum setting performance are particle fineness, impurities, raw material source (natural or synthetic gypsum). These impact upon gypsum crystal nucleation. The efficiency of tartaric retarders in plaster systems is influenced by their chemistry and derivation. Tartaric acid and tartaric acid salts have a good retardation effect on the setting of plaster especially in the high-alkaline range. Tartaric Acid, in most cases, requires additional Calcium Hydroxide in order to function as a retardant. Tartaric acid is most effective at alkaline pH values > 11.5 ( high-alkaline range ). Please contact us for further information.