Ask the Expert Question-and-Answer Archive

by Ron Joseph

August, 2008

Sagging

Q: Is there any relationship between the the useful life of a resin, the time vs viscosity and the sagging?

A: I have not seen any literature on such a relationship. Sagging is also a function of paint film thickness. In addition, you need to differentiate between dynamic, absolute and kinematic viscosity. The following article http://www.engineeringtoolbox.com/dynamic-absolute-kinematic-viscosity-d_412.html provides a useful tool in understanding the different forms in which viscosity is measured and the properties of non-Newtonian fluids. A thixotropic paint will be more resistant to sagging than the same formulation that does not contain a thixotropic agent. Therefore, I believe you need to be more specific about your requirements. Also, I'm am not aware that the viscosity of all resins change with age, or that such changes are consistent from one resin to another.

Regards,

Ron Joseph