Viscosity
What is Viscosity Testing?
Viscosity describes a fluid’s resistance to flow—often referred to as “thickness.” Viscosity testing measures how easily a liquid or semi-liquid material flows under defined conditions such as temperature, shear rate, and time. It is a key QC and performance parameter for many products and process materials, impacting mixing, pumping, coating, printing, dispensing, and final appearance.
Viscosity testing is widely used for chemicals, solvents, oils, coatings, inks, adhesives, resins, slurries, and personal care products.
What Viscosity Testing Can Help You Solve
QC release testing and specification compliance (incoming and finished goods)
Batch-to-batch consistency and supplier comparison
Process control for mixing, dilution, and solvent loss/evaporation effects
Application performance (coat/print/dispense behavior; leveling vs sag)
Troubleshooting defects linked to flow (streaks, orange peel, dripping, stringing, poor coverage)
Stability monitoring (viscosity drift during aging or storage)
Typical Applications
Coatings & paints: application viscosity, leveling control, defect prevention
Inks & printing fluids: printability, screen/gravure performance, consistency
Adhesives & sealants: dispensing behavior, open time sensitivity, filler loading effects
Oils & lubricants: viscosity grade verification (project-dependent)
Battery slurries & suspensions: coating uniformity and processability (project-dependent)
Cosmetics & consumer products: texture and stability control
Process chemicals: concentration/dilution monitoring via viscosity trend (project-dependent)
Test Capabilities & What You Receive
Common Measurement Approaches (project-dependent)
Single-point viscosity at a specified temperature and speed (routine QC)
Viscosity vs shear rate (flow behavior screening: Newtonian vs shear-thinning)
Temperature-dependent viscosity (viscosity vs temperature curve)
Time-dependent behavior (stability under shear; thixotropy screening—if applicable)
Comparative testing across lots, suppliers, or aging conditions
Deliverables
Viscosity results with units (e.g., mPa·s / cP, Pa·s)
Test conditions (temperature, method, spindle/geometry, speed/shear condition, time)
Plots (optional) for shear-rate or temperature sweeps
Comparison summary and pass/fail vs your specification (if provided)
Sample Requirements
Sample types: liquids, solutions, emulsions, gels, pastes, slurries (method dependent)
Typical volume: commonly 20–200 mL (depends on viscosity range and instrument geometry)
Condition: homogeneous; minimize bubbles; note any settling or phase separation
Packaging: sealed container to prevent evaporation; label clearly
Information to provide: expected viscosity range, target temperature, product type (Newtonian vs shear-thinning if known), and any relevant QC spec
Workflow
Requirement review (QC point vs flow curve; temperature; acceptance criteria)
Method selection (instrument/geometry, speed or shear-rate plan, conditioning protocol)
Sample conditioning (mixing, degassing, temperature equilibration)
Measurement with defined timing and shear history
Data processing (averaging, repeatability checks, curve fitting if needed)
Reporting (results + conditions + conclusions)
FAQs
Why does viscosity change with temperature?
Most fluids become less viscous at higher temperature. That’s why viscosity must be reported at a specified temperature and controlled during testing.
What’s the difference between viscosity testing and rheology?
Viscosity testing often reports a single value under defined conditions for QC. Rheology expands this to include viscoelasticity, yield stress, thixotropy, and curing behavior, which can be critical for complex materials.
Can you test shear-thinning materials like inks or slurries?
Yes. For non-Newtonian materials, a flow curve (viscosity vs shear rate) is often more meaningful than a single-point value.
Do bubbles or particles affect viscosity measurements?
They can. Bubbles and settling can distort readings. We recommend proper mixing, gentle degassing, and consistent sample handling.
How many replicates do you run?
Replicates can be tailored to your QC needs. For routine screening, duplicates/triplicates are common; more may be used for method development or tight specs.
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