This Part covers the determination of the viscosity of Newtonian or near-Newtonian paints, varnishes, lacquers, and related liquid materials with the Ford-type efflux viscosity cup.
1.2 The cup-orifice combination (Ford No. 2, No. 3 or No. 4) is selected to provide an efflux time within the range 20 to 100 s. When the time of efflux is beyond this range, accurate temperature control is difficult. Any departure from Newtonian behaviour may result in a lack of reproducibility because of the difficulty of judging the break in the stream.