TCP Global Brand SG244 Liquid Thickness & Viscosity Measuring Cup Ford # 4 Four, Viscosimeter to Measure Paint The Ford # 4 cup is a portable device for quickly checking and measuring the viscosity or thickness of paint, varnish, lacquer, stains, inks, syrups, liquids and more. Cup allows you to verify coating viscosity prior to painting, so you can fully atomize the paint spray, helping you achieve a flawless finish. The Ford viscosity cup is a simple gravity device that permits the timed flow of a known volume of liquid passing through an orifice located at the bottom. To determine the viscosity of a liquid, the cup is dipped and completely filled with the substance. After lifting the cup out of the substance the user measures the time until the liquid streaming out of it breaks up, this is the corresponding "efflux time".