Mesh count is the number of openings per linear inch, and it is not the same as aperture. Two meshes with the same count but different wire diameters have different openings, because the thicker wire occupies more of the pitch. Aperture is what determines the particle size that passes, so specify count, wire diameter and aperture together.

Plain weave interlaces one over one and gives square apertures - the general-purpose construction. Twill passes each wire over two and under two, so heavier wire can be used at a given count, giving finer apertures with more strength. Dutch weaves use different warp and weft diameters to reach very fine filtration ratings in the micron range.

It governs flow rate and pressure drop. Two meshes can filter to the same particle size while differing substantially in the proportion of the surface that is actually open, and the one with less open area will blind sooner and cost more in pumping energy. For filtration duty, open area is as important as aperture.

Stainless steel 304 and 316 are the mainstay, chosen for corrosion resistance, strength and food and pharmaceutical compatibility. Brass, bronze and copper are used for decorative and electrical screening work, nickel alloys for chemically severe duty, and plain or galvanised mild steel where cost governs and the environment is benign.

Because the wires are only interlaced, not fixed at their intersections, so nothing holds a wire once its ends are cut. Any cut edge needs terminating - framing, edge binding, welding or a crimped edge strip. This is the principal practical difference from welded mesh, which holds its shape when cut.

Yes. Test sieve cloth is manufactured and certified to defined aperture tolerances under international standards, and sieves are supplied with inspection or calibration certificates where the results must be traceable. General-purpose industrial mesh is not held to those tolerances, so a certified sieve cloth should be specified for standards work.

In rolls of standard widths and lengths, and as cut pieces, discs and framed panels. Fine filtration meshes are also supplied laminated or sintered into multi-layer packs that combine a fine filtration layer with coarser support layers, giving the rating of the fine mesh with far greater mechanical strength.