Keep the powder packing factor with the capillary uptake slope before interpreting a Washburn result as a change in wettability.
Identify the Material Response
KRUSS gives the powder Washburn relation with squared absorbed mass increasing in proportion to time, packing factor, liquid density squared and surface tension times contact-angle cosine, divided by viscosity. Primary reference: powder capillary uptake model.
Review a Hypothetical Comparison
In a hypothetical compatible comparison, liquid properties and packing factor are held equal. If the second mass-squared slope is half the first, its contact-angle cosine is half the first. With a deliberately assumed perfectly wetting first state, the second cosine is 0.5 and the inferred angle is 60 degrees. Changing packing would undermine that inference.
Keep the Evidence with the Decision
Record the slope interval, powder preparation and packing-factor basis alongside liquid temperature and properties. Separate measured slope from the calculated angle so a new input cannot silently look like new raw evidence. Identify whether the liquid and powder form the same relevant contact system; dissolution or changing structure can complicate the ideal capillary interpretation.
The hypothetical reference is a model assumption, not a recommended liquid or preparation procedure. No packing-factor value, physical experiment or HM material result is supplied. The practical decision is whether the compared slopes support an angle interpretation under their stated assumptions. If those assumptions are unresolved, retain the uptake observation and request the missing method evidence instead of publishing a spurious material contact angle.
Can the capillary uptake slope distinguish wettability after accounting for powder packing and liquid properties?
This blank worksheet is for your own project. It contains no H M machine trial result.
| Review field | Reference or result | Responsible person |
|---|---|---|
| Mass-squared slope and time interval | To complete | To complete |
| Packing-factor/preparation basis | To complete | To complete |
| Liquid density, tension and viscosity | To complete | To complete |
| Contact-system and model assumptions | To complete | To complete |
Customer Questions
Does half slope always mean a 60-degree angle?
No. That follows only from the stated equal-input and reference assumptions.
Can packing changes affect the slope?
Yes. Retain the packing factor.
Is a specific test liquid recommended here?
No. The actual method must establish suitability.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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