This part of EN 12607 specifies a method for measuring the combined effects of heat and air on a thin moving film of bitumen or bituminous binder, simulating the hardening which most bituminous binders undergo during mixing in an asphalt mixing plant. The method is suitable for other bituminous binders than paving grade bitumen, but the reference temperature might give excessive hardening that does not resemble real conditions during mixing at the plant. The method may not represent the hardening that occurs during mixing of warm mix binders.The method is referred to as RFT, i.e. Rotating Flask Test.