 Oils that are used include heavy residual oil ( HRO ) , animal fats , vegetable fats , and synthetic fats . <unk> are gelatinous at room temperature , but at the high temperatures found in die casting , they form a thin film . Other substances are added to control the emulsions viscosity and thermal properties ; these include graphite , aluminium , and mica . Other chemical additives are used to inhibit rusting and oxidation . <unk> are added to water @-@ based lubricants , so that oil based additives can be mixed into the water ; these include soap , alcohol esters , and ethylene oxides . 
