What does it mean for emulsions to be considered "static"?

When emulsions are described as "static," it indicates that they will not flow even under the influence of external forces, such as flame or infrared heat. This characteristic is essential in certain applications, particularly in roofing materials, where the stability and integrity of the membrane must be maintained during installation and throughout its service life. Static emulsions can resist melting or flowing away, ensuring they maintain their form and can effectively bond to surfaces or other materials as needed.

High viscosity relates more to the thickness and resistance to flow of a substance, but it does not solely define a static emulsion, as this could also imply a degree of flow under certain conditions. Therefore, while viscosity can be a factor, the key defining characteristic of a static emulsion is its inability to flow regardless of external influences.