"The viscosity of this glue is 5000 mPa·s" — if this is all the description your lab has for a adhesive's rheological properties, then you're making 80% of your R&D decisions with only 20% of the information. Single-point viscosity tells you the material's resistance at one shear rate, but adhesives/coatings during application can experience shear rates spanning 5–6 orders of magnitude (from zero shear during static storage to 10,000 s⁻¹ during high-speed coating). Single-point viscosity cannot describe this process at all.  

What really drives R&D forward are three rheological parameters:  

Flow Curve — the relationship between viscosity and shear rate. Most polymer systems are shear-thinning (viscosity decreases as shear increases). A complete flow curve describes the material's viscosity behavior from rest to high-speed coating. By fitting the flow curve with a power-law model, you can predict viscosity at any shear rate.  

Thixotropy — the time-dependent recovery of the structure after shearing. Using a thixotropy loop test (shear rate ramp-up and ramp-down cycle), you can quantitatively evaluate how quickly the material recovers to a "non-sag" state after coating. The larger the loop area, the slower the structure recovers. This directly guides the design of coating and adhesive application processes.  

Yield Stress — the minimum force required for the material to start flowing. Adhesives with yield stress hold their shape when still (no sagging) but flow and can be applied once the yield stress is exceeded. Anti-sag properties of coatings, squeezability of toothpaste, and print resolution of conductive pastes — these all rely on yield stress.  

Dehuisci (www.dehuisci.com) represents TA Instruments rotational rheometers, helping your R&D move from "single-point viscosity" to "full rheological analysis." Call: 0512-67071902.