A micron or micrometer is one thousandth of a millimeter. Our mesh openings and wire diameters are shown in microns.
1 millimeter = 1000 micron

Warp wires
Warp wires are wires that run in the longitudinal direction of the roll.

Weft wires
Weft wires are wires that run in the width direction of the roll.

Mesh opening
The mesh opening is the size of the openings of the mesh or the distance between two wires. We always indicate mesh openings in microns.
The mesh opening can also be displayed with the mesh number. This number indicates the number of openings per linear inch (25,4mm), measured from center to center wire. To determine the mesh number of a mesh type, we measure from the center of a wire to a point one inch away from it and count the number of openings at this distance.
The formula for calculating the mesh opening is: (25,4 / mesh number) – wire thickness

When referring to Dutch weave, we do not speak about mesh openings, but retention. Retention is difficult to calculate, because it depends on various factors, including the pressure, the shape of the particles to be sieved etcetera. The retention of Dutch weave is therefore usually determined experimentally.

Open area (%)
If both the mesh number and the wire thickness are known, the mesh opening and the open area (%) can be calculated for each type of mesh.
Formula for the open area in percentages: 100 x (M² / ((M+D)²))

M = mesh opening
D= wire diameter

When referring to selvedge, the side which is formed by the weft wire is meant. When we speak about mesh with selvedge, the weft wire forms a loop around the outer warp wire.