Slow Curing or SC soluble bitumens are another type of soluble bitumens that are produced using heavy solvents such as diesel, fuel oil or black oil. Of course, under normal conditions, these solvents do not evaporate and only undergo molecular deformation. This type of bitumen is used to make base and subbase layers, insulation and sealing of hydraulic structures. It takes a long time for slow-curing bitumens to fully set after use. In fact, these bitumens do not set under normal weather conditions, but their molecular deformation is relatively gradual and long. Slow-curing bitumens are graded into four types. Slow-curing bitumens are classified into four types according to their viscosity: SC-70, SC-250, SC-800, SC-3000, where the suffix numbers indicate the slow-curing bitumen in centistokes. Their minimum viscosity is at 60 degrees Celsius, and for the most dilute type, or -30 SC, it is equivalent to 30 centistokes, and for the most concentrated type, or -3000 SC, it is equivalent to 3000 centistokes.