The viscosity of a hot melt adhesive is important for processing with application devices. It also affects the hot tack of a hot melt adhesive and its ability to fill gaps or not be squeezed out.
The viscosity of hot melt adhesives is determined using a rotary shear viscometer in conjunction with a temperature-controlled heating unit. The viscosity of hot melt adhesives depends on their temperature. The viscosity is lower at higher temperatures.