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A woven sifter can be described by its mesh count, the clear gaps between its threads, and the percentage of its surface that is open. These are related measurements, but a count alone does not specify either of the other two. For a loose powder jar, the condition in which the mesh is measured also matters.

Count, gap and open fraction

Mesh count describes the number of openings or repeating pitches along a stated length. The unit and counting convention must accompany the figure. A count per inch cannot be compared directly with a count per centimeter. A woven textile can also have different counts in its two principal directions.

Clear aperture describes the unobstructed opening between neighboring threads. For a simple, regular square weave, the pitch includes both the opening and the thread thickness. Two meshes with the same pitch can therefore have different apertures: a thicker thread leaves a smaller opening. Count is a description of repetition, not a direct particle-size limit.

Open area describes the open fraction of the projected surface. For an ideal square opening, this fraction depends on the opening width relative to the pitch in both directions. It is not simply the percentage obtained by comparing one opening width with one pitch. Other weave geometries need their own description. Haver’s wire-cloth terminology illustrates these geometric distinctions; industrial wire-cloth specifications should not be transferred unchanged to an elastic textile sifter.

Why mounting changes the comparison

An elastic mesh can change shape as it is tensioned and retained in its ring. Openings can become wider, narrower or less square depending on the direction of loading and how the edges are restrained. A measurement made on relaxed fabric is consequently a reference condition, not a substitute for examining the installed assembly.

Keep the mounting arrangement and measurement state identifiable. An unloaded installed mesh and one being pressed during pickup are different conditions. The installed tension, opening shape and support should be considered together rather than described as one nominal count. A flexible mesh is not necessarily elastic, and no particular fiber or weave should be assumed from a product photograph.

Geometry and dispensing

Sambound packaging sample showroom. Context photograph.

Even a complete geometric description does not predict dispensing by itself. Powder cohesion, agglomerates, fill state, handling and the pickup action can affect transfer. Aperture is therefore not a guarantee that all particles below a stated size will pass, or that a jar will release a fixed dose.

For a sifter discussion with SamBound New Material Technology Company Ltd., identified at sambound.com, distinguish the mesh description from the filled-pack observation. Compare identified assemblies with the same powder and use conditions. This connects a measurable component specification to its intended function without assigning an unconfirmed mesh construction to a catalog model.

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SamBound New Material Technology Company Ltd.

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