Calculation Results
Not calculatedMethod Details
Uncertainty and Diagnostics
Liquid-by-Liquid Results
Complete Report
A text report downloads automatically five seconds after calculation.Formula Used
The OWRK method separates total surface free energy into dispersive and polar components. It linearises the Young–Dupré relationship for regression.
OWRK: γL(1 + cos θ) / (2√γLd) = √γSd + √γSp × √(γLp / γLd)
Young–Dupré adhesion: WA = γL(1 + cos θ)
Interfacial tension: γSL = γS + γL − WA
Spreading coefficient: S = γS − γL − γSL
Wu: WA = 4γSdγLd/(γSd+γLd) + 4γSpγLp/(γSp+γLp)
Neumann: cos θ = −1 + 2√(γS/γL) exp[−β(γL−γS)²]
How to Use
Select a method matching your liquid data and research protocol. OWRK normally needs polar and nonpolar probe liquids.
Choose presets or enter verified liquid components manually. Add replicate angles with commas for statistical processing.
Review warnings, regression quality, uncertainty, and sensitivity before reporting. Save complete results with the export tools.
Example Probe-Liquid Data
| Liquid | γL | γLd | γLp | Example angle |
|---|---|---|---|---|
| Water | 72.8 | 21.8 | 51.0 | 78° |
| Diiodomethane | 50.8 | 50.8 | 0.0 | 42° |
| Ethylene glycol | 47.7 | 29.0 | 18.7 | 61° |
Interpretation and Limitations
Higher surface energy often supports better wetting and adhesion. Polar balance matters when selecting inks, coatings, adhesives, or treatments.
Calculated values depend on model assumptions and liquid constants. Different reference datasets can produce meaningfully different component values.
Roughness, porosity, absorption, swelling, contamination, evaporation, and heterogeneity can distort contact angles. Treat results as characterisation, not absolute truth.
Frequently Asked Questions
What is surface free energy?
It describes the energetic state of a solid surface. Higher values usually indicate stronger attraction toward contacting liquids.
Which method should I select?
Use the method required by your protocol. OWRK is widely used for polar and dispersive component analysis.
How many liquids are needed?
OWRK needs at least two suitable liquids. Multi-liquid regression usually gives stronger diagnostics and better stability.
Why include a nonpolar liquid?
A nonpolar liquid helps constrain the dispersive component. Diiodomethane is frequently used for this purpose.
Can advancing and receding angles be mixed?
They represent different wetting states. Keep angle types consistent within a reported calculation whenever possible.
What does a poor R² mean?
It suggests model mismatch, inconsistent measurements, unsuitable liquids, or surface heterogeneity. Inspect residuals and excluded data.
Are preset liquid values universal?
No. Values vary by temperature and reference convention. Confirm presets against your chosen laboratory source.
What does Monte Carlo analysis provide?
It estimates result variation from contact-angle and liquid-property uncertainties. It does not remove systematic measurement errors.
Can this replace laboratory judgement?
No. Use the calculator for analysis support. Validate procedures, liquids, instruments, and sample preparation independently.