The mechanical properties of gelatin gels are very sensitive to temperature variations, the previous thermal history of the gel, and time. These gels exist over only a small temperature range, the upper limit being the melting point of the gel, which depends on gelatin grade and concentration but is typically less than 35 °C (95 °F) and the lower limit the freezing point at which ice crystallizes. The upper melting point is below human body temperature, a factor which is important for mouthfeel of foods produced with gelatin.[2] The viscosity of the gelatin/water mixture is greatest when the gelatin concentration is high and the mixture is kept cool at about 4 °C (39 °F). The gel strength is quantified using the Bloom test.