Specify the particle size that matches your application, but do not rely on a single number unless your process truly depends on an average. In most B2B orders, I recommend stating the target size range, the distribution metric—such as D10, D50, and D90—and the measurement method. Also clarify whether you mean primary particles, agglomerates, or dispersed particles, since these can produce different results. There is no universal “correct” size: your material, application, and test conditions determine the specification.
Particle size is a measurement of the dimensions of particles in a material, but reported results depend on how the sample is prepared and measured. For a powder, primary particles may be joined into larger agglomerates. A measurement made after dispersion may therefore differ from one made on the as-received powder.
For clarity, I suggest treating particle size as a set of linked requirements rather than an isolated value. Your purchase specification should identify the target distribution, the particle population being measured, and the method used to determine it. If a supplier cannot measure the material by your preferred method, agree on an alternative and its limitations before ordering.
A D-value describes a point in a particle-size distribution. For example, D50 is the size below which 50% of the measured distribution falls, according to the stated basis; D10 and D90 describe the corresponding 10% and 90% points. These values help buyers see more of the distribution than a single average can show.
Always state whether the distribution is reported by number, volume, or another basis. Results can differ because these methods weight particle populations differently. If a broad distribution would cause performance or processing problems, specify an acceptable range for relevant percentiles rather than relying on D50 alone.
Primary particle size refers to individual particles, while an agglomerate is a cluster of particles that may behave as a larger unit during handling or processing. In some applications, primary size affects surface-related behavior, while the size of agglomerates affects mixing, flow, or dispersion. These relationships depend on the material and process, so buyers should avoid assuming that one measurement represents both.
When ordering a powder, state whether the requirement applies to the as-received material or to particles after a defined dispersion procedure. For a dispersion, include relevant conditions such as the liquid medium and preparation steps. If you need both primary-particle information and dispersed-size performance, list them as separate requirements.
Work backward from the function the material must perform. Consider whether the key requirement relates to surface area, optical behavior, electrical or thermal performance, suspension stability, flow, or compatibility with another ingredient. Particle size may influence these properties, but it is not the only factor; composition, shape, surface treatment, and processing conditions may also matter.
For example, a formulation that must remain uniformly dispersed may need limits on the larger end of its size distribution, while a powder-processing operation may prioritize flow and handling. A buyer should first identify the failure mode that particle size is meant to prevent. This keeps the specification connected to a measurable business or technical need.
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Use units consistently and make the micro- or nanoscale requirement explicit. One micrometer (1 μm) equals 1,000 nanometers (1,000 nm), so writing the unit beside every value helps prevent conversion errors. Avoid mixing units within a single specification unless the conversion is clearly stated.
As an illustrative format—not a recommendation for every material—a buyer might request a D50 target of 500 nm with a separately agreed D90 ceiling. The actual values should come from application trials, design requirements, or an established process window. If you have no validated target, request representative samples or discuss a feasibility range with the supplier before locking in a purchase specification.
A useful inquiry gives the supplier enough detail to confirm whether the requested size is measurable and commercially practical. I recommend separating the target from the test conditions and acceptance criteria. If the method, sample preparation, or distribution basis is left open, two parties may report different results without either measurement being inherently incorrect.
| Specification item | What to state |
|---|---|
| Target size | Range or target value, with units such as μm or nm |
| Distribution | Required percentiles, such as D10, D50, and/or D90, and the reporting basis |
| Particle condition | Primary particles, as-received powder, agglomerates, or dispersed particles |
| Measurement | Agreed instrument or method, sample preparation, and reporting conditions |
| Acceptance | Permitted variation, sampling plan, and documentation required for the order |
Ask the supplier to confirm how the result will be reported and whether the method is suitable for the material’s size range and form. Different measurement techniques do not necessarily measure the same physical feature, and sample preparation can change the observed distribution. If you require a certificate or test report, agree on its contents and acceptance criteria before production rather than assuming a particular format is included.
Before issuing a purchase order, confirm that the size requirement is linked to a measurable outcome and that the supplier understands the intended use. Share the material form, required quantity, downstream process, and any constraints on dispersion or handling that affect measurement. Ask which parts of the request the supplier can verify and which require customer-side validation.
At Azeal Materials, we encourage buyers to discuss particle-size targets alongside material grade, application, and test expectations. This allows both sides to clarify whether a requested specification is technically meaningful and how it should be documented. For a new or sensitive application, start with a written specification and discuss sample evaluation before setting a production order.
The right particle size to specify is the range and distribution your application requires—not a universal micro- or nanoscale value. State the target in clear units, define the relevant percentiles and reporting basis, and distinguish primary particles from agglomerates or dispersed particles. Then agree on the measurement method, sample preparation, and acceptance criteria with your supplier.
Your next step is to identify the performance requirement that particle size must support, convert it into a measurable range, and ask the supplier to confirm feasibility and reporting details. Azeal Materials can discuss your material and specification needs to help you prepare a clearer inquiry and evaluate the next steps for sourcing.
For more information, please visit What Particle Size Should Buyers Specify When Ordering Micro and Nano Materials?.
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