Powder property
Particle size distribution
The full distribution matters more than one median value
Particle size distribution describes how particle quantity is distributed across size classes under a defined measurement method and reporting basis. D10, D50, D90, fines, oversize, span, and curve shape become useful when they are connected to the process behavior under investigation.
Core concept
Particle size is a distribution, not a single diameter
A powder contains a population of particles rather than one representative size. Percentiles summarize parts of that population, but they do not show the reporting basis, curve shape, shoulders, or whether the sample contained intact agglomerates. Laser diffraction, sieving, and image analysis respond to particles through different physical definitions. Their results can all be valid while producing different numerical distributions. Interpret the full curve together with preparation, dispersion, sampling, and the process question. A stable D50 does not rule out a meaningful change in fines or oversize.
What controls it
Six features shape how particle size distribution is interpreted
The diagnostic value comes from identifying which part of the distribution changed, whether that change is real, and why it matters to the operation.
States and interpretation
The same powder can produce different reported distributions
Match the measurement principle and preparation route to the particle state relevant to the decision.
| Measurement state | What is represented | Interpretation risk | Useful control |
|---|---|---|---|
| Dry, gently dispersed | Loose particles and weak structures that survive handling | Residual agglomerates may appear as coarse material | Define pressure and feed conditions |
| Wet, strongly dispersed | Particles and agglomerates remaining after a defined wet-dispersion protocol | Fragile process structures may be destroyed | Document liquid, chemistry, sonication, and time |
| Sieved by mass | Fractions retained by physical apertures | Shape and passage orientation affect retention | Control sample mass, time, loading, and sieve condition |
| Imaged by number | Individual projected particle dimensions and shape | Rare coarse particles may be poorly represented | Report particle count and descriptor definition |
How to measure it
Choose a measurement by the size question
Particle size results are method-dependent. Select the principle, preparation, and reporting basis that can resolve the process uncertainty.
Where it matters
Particle size distribution becomes a process constraint
Different parts of the distribution control different operations, so the useful specification depends on where the powder must perform.
Go deeper
Three practical routes into particle size distribution
Explore how distribution tails, measurement basis, and particle shape change the conclusions drawn from particle size data.
Need the measurement, not just the guidance?
If the remaining uncertainty concerns particle-size distribution, tail fractions, sampling, dispersion, or disagreement between methods, select the measurement around the material state and process decision. PowderTechnology.info can help define the test sequence, sample conditions, and interpretation route. For laboratory support, explore our Delft Solids Solutions partner page or visit Delft Solids Solutions directly.
