Strength of fat crystal networks in oil increases at elevated temperature due to increased adhesion between partially melted crystal surfaces. This strong adhesion, in combination with low oil viscosity (weak hydrodynamic force), is the reason for extensive fat crystal flocculation at elevated temperatures. The crystal flocs likely sinter, dramatically increasing the thickness of semisolid fats. Crystal growth also occurs. The described temperature induced crystal changes may be suppressed by a controlled sintering process at low temperature. Emulsifiers, such as sorbitan esters of tristearate, also suppress the temperature induced changes. Fat crystals can be used as thickeners or gelling agents for triglyceride oils in various applications. It is possible to direct the thickening to a specific temperature, and control the degree of thickening, by choice of fat phase composition, additives, tempering conditions and crystallization technique.