DETERMINATION OF VISCOSITY

摘要

Viscosity is an indication of a material's ability to resist flow. Flow characteristics of liquids relate directly to the amount of internal friction. Anything that will influence internal friction — such as solvents, temperature, or mixing — will influence flow. Similarly, flow characteristics determine how well a material will atomize, how well it will "flow out" on the work, and the type of equipment necessary to move it. Viscosity control is essential to obtain uniform finish quality from day to day and job to job. Your material supplier will recommend the best viscosity to apply material chosen for your job — stick with it. There are many methods by which viscosity determinations can be made. Each method may have one or more units of measurement. The paint user will most often use the efflux method. Both Zahn and Ford cups are available with different size orifices to provide a wide range of viscosity measurements. The two most widely used for paint are the Zahn #2 and the Ford #4. Equipment required for viscosity measurement includes a viscosity cup, stopwatch, and accessories as illustrated in Fig. 1.