Mesh size guide for mineral powder

Mesh size is the single most asked specification in mineral powder ordering, and also the one most often misread. This guide explains what it means, how it maps to microns, and how to choose it without over- or under-grinding.

What does mesh size mean?

Mesh is the number of openings per linear inch in the screening cloth used to classify the powder. A higher mesh number means a finer powder: 200 mesh passes through 200 holes per inch, 1250 mesh through 1250. It is a screen classification, not a single particle size.

Because mineral particles are irregular, mesh is complemented by D50 — the particle diameter at which 50% of the sample is finer. We report both. For our ground calcium carbonate, for example, D50 ranges from about 2.9 to 7.5 µm depending on the grade.

Mesh to microns, roughly

As a rule of thumb, 200 mesh ≈ 74 µm, 325 mesh ≈ 45 µm, 400 mesh ≈ 38 µm, 800 mesh ≈ 18 µm, 1250 mesh ≈ 10 µm, 2500 mesh ≈ 5 µm. These are approximations for typical mineral powders and vary with particle shape and density.

We can also supply by micron specification or by a required D50 / particle-size distribution rather than by mesh, which is more precise for closed-tolerance formulations.

Common ranges by product

Talc: 325–3000 mesh. Calcium carbonate: 10 mesh (calcite sand) to 3000 mesh (ultra-fine GCC). Dolomite: 200–2000 mesh. Magnesia products span from coarse grain to micro-fine. Snow white sand is supplied at 20–40 and 40–80 mesh. Landscaping pebbles are graded by millimetre, 3–5 mm to 60–90 mm.

If your process names a specific mesh, send it; if it names a performance target (opacity, slip, reinforcement), tell us the application and we will match the closest grade.

How to choose without over-grinding

Finer is not always better. Beyond a point, extra fineness raises cost, increases oil absorption and can hurt dispersion. Choose the coarsest grade that still meets your performance target, then let us tune from there.

For a first order, request free samples at two adjacent mesh sizes and test both — the difference is often larger in your process than the number suggests.