The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal term "thickness": for example, paint has a higher viscosity than water. Based on viscosity, you can determine how much thinner to add to the paint, how the material will flow, and how to adjust the spray gun
Measure the viscosity of your paint
The viscosity can i.a. is measured with a viscosity cup by pouring a given amount into the viscosity cup and then running out of the hole at the bottom of the cup. Time is taken for how long it takes the paint to run through the hole in the cup. The faster the paint is to flow through the cup, the lower the viscosity. So the more viscous a material is, the higher the viscosity.
The difference on viscosity meter
The difference between the different types of cups is usually the volume and nozzle opening as well as the design of the sides. The temperature of the paint also affects the viscosity. You can measure the paint temperature with a paint thermometer or a laser temperature meter.