The Ford Cup B-4, also known as the Ford Cup Viscometer B-4, is a testing instrument used to measure the viscosity or thickness of liquids such as paints, varnishes, inks, chemicals, and lubricants. It is one of the most commonly used viscosity measuring tools in laboratories and industrial production units. The cup is generally made from aluminum, brass, or stainless steel and contains a standard 4 mm opening at the bottom through which the liquid flows. The time taken for the liquid to flow out is measured in seconds, and this helps determine the viscosity of the material.

The Ford Cup B-4 is widely used in industries where the correct thickness of liquid products is important. It is mainly used in the paint and coating industry to check the consistency of paints before spraying or application. It is also used in printing ink manufacturing, chemical industries, automotive paint shops, adhesive manufacturing, and research laboratories. In these industries, maintaining the correct viscosity is necessary for achieving smooth finishing, proper coating, and high-quality products.