As you may have seen on product data sheets or specifications, each flux is tested per industry standards for different parameters. One characteristic that is important to customers is viscosity. There are various ways to measure the viscosity of a tacky-type flux, the most common being the J-STD T-bar method. This testing uses a rotating spindle to feed-back the force needed to shear thought the flux. For a more application-realistic measurement, we also use the cone and plate method to test viscosity. This test method employs a rotating disc that works in a similar manner to T-bar feed-back, but tests a film of material between the base cup and the disc. I expect future test method standards to target the cone and plate method, once the industry catches up.