Professional Detailing2 min read

DLS Particle Size and Electron Microscopy: Why the Numbers Can Differ

Dynamic light scattering reports size through particle motion in a liquid. That hydrodynamic measurement need not match a dimension measured from an image of a prepared particle sample. A difference requires interpretation before either result is rejected.

Updated · NANOLAB Knowledge

The key distinction

Malvern Panalytical explains hydrodynamic diameter as an equivalent size related to diffusion. Buyers should therefore establish what each technique measured and how the sample was prepared. A coating ingredient's size report should retain the method, sample state and analysis basis rather than presenting an unexplained nanometre value as a universal physical dimension.

Practical checks

  1. Obtain the complete reports and sample preparation descriptions.
  2. Ask whether the same material and batch were examined under comparable conditions.
  3. Request an explanation of the expected relationship between the techniques before creating an acceptance threshold.

Example

Illustrative example: a supplier provides a liquid-state size report and a separate microscopy image. Their values differ, but the buyer has not established whether the sample was diluted or dried differently. Comparing the raw numbers alone cannot identify the cause or establish a product defect.

Scope and limits

Particle-size information does not prove the performance of a finished coating. It also does not reveal a proprietary formula. Avoid using a single measurement to claim superior protection, penetration or durability without evidence that directly evaluates the claimed outcome.

Related guidance

Technical references: Malvern Panalytical: Introduction to DLS. These sources describe their stated methods or products; they do not certify NANOLAB products or establish compatibility with an unlisted surface.

Ask NANOLAB about the exact product and intended use. Use the current product documentation for formulation-specific instructions.

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Can a Paint Gauge Measure a Thin Ceramic Coating?

Review the limits of paint-gauge before-and-after readings when assessing a thin ceramic coating, including total film thickness and measurement uncertainty.

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Viscosity Inputs in DLS: A Sample Setting Can Change the Size Result

A dynamic light scattering result depends on information about the liquid surrounding the particles, including viscosity. Using an inappropriate input can affect the calculated size even when the instrument completes the measurement successfully.