Bitumen heating
When heating bitumen, when it begins to foam, releasing impurities should be removed from its surface. This is usually done with a tin can with a broken hole. When bitumen stops foaming, it is stopped heating. The surface of the bitumen should be mirrored, and the whole mass looks homogeneous. It must be borne in mind that it is impossible to overheat bitumen, as coke can form. Signs of overheating: the formation of greenish-yellow smoke and the appearance on the surface of the bubbles. When heated more than 240 degrees, the mass may light up.