Viscosity
Definition
Flow resistance of adhesive, affecting coating and bonding.
Historical Background
1940s: rotational viscometers replaced inaccurate drip-time method.
Example
Water = low viscosity; honey = high. Determines coating uniformity.
Formula
Dynamic Viscosity (Pa.s) = Shear Stress (Pa) / Shear Rate (s-1)
Core Concepts
Governs coating, wetting, filling behavior. 10C increase reduces viscosity ~50%.
Extended Applications
Spray: 50-500 mPa.s; roll-coating: 1,000-5,000; doctor-blade: 10,000-50,000; screen printing: thixotropic.