The common starting point for all bitumen is the distillation of a carefully selected type, or types, or selected blends of crude oil – as only approximately 10–15% of crude oils are suitable for producing bitumen that will meet precise engineering specifications.  

The properties, and hence the applications, of these different types of bitumen vary according to a combination of factors, are distilled from; which refining method is used; and what, if anything such as an additive, is blended into the bitumen within the production process. All circumstances and production technologies are carefully investigated before, and checked during the production, as described in the site quality management plan.