It passes the expanded sheet through a cold rolling mill, which presses the angled strands down until they lie in the plane of the sheet.

The diamond pattern itself is not changed - the same openings, the same arrangement, the same strand count. What changes is the third dimension. In standard material the strands are inclined, so the panel has a raised texture and an overall thickness noticeably greater than the metal it is made from. After rolling, the strands lie flat and the panel's overall thickness drops close to the strand thickness itself.

Two side effects follow. The rolling works the metal, so it stretches the panel slightly along its length - a flattened panel is longer than the standard panel it was made from. And the strand thickness itself changes under the rolls, which is why flattened material quotes an overall thickness rather than simply inheriting the parent sheet gauge.

When the panel has to be flat, has to look refined, or has to sit against something.

The clearest case is any panel mounted flush - against a frame, a backing board, glazing, or another panel. Standard expanded metal has a raised face that will not seat properly and will leave gaps or rock on its mounting.

The second case is appearance. Flattened material reads as a clean, precise mesh rather than an industrial one, which is why it dominates architectural screens, ceiling and wall panels, furniture, shopfitting and retail display.

The third is handling and cleaning. A flat surface can be wiped down and does not catch on gloves, clothing or product passing across it, which matters in food, laboratory and retail environments.

Stay with standard where the panel is doing structural or anti-slip work, or where cost per square metre is the governing factor.

Enough to matter in the design, though it varies with the grade and the geometry.

Standard expanded metal gets much of its rigidity from the strands standing out of plane, which gives the panel an effective depth greater than the metal thickness. Rolling the strands flat removes that depth, so the panel's resistance to bending falls back towards what a thin perforated sheet of similar mass would offer.

In design terms that means a flattened panel needs support at closer centres than the standard panel it was made from, and a design that substitutes one for the other without revisiting the framing will produce a panel that sags or drums.

This is also why flattened material is not used for walkways and platforms. The load tables published for expanded grating apply to the standard raised form, and they should not be applied to flattened material.

No, and it should not be substituted for standard grating grades under any circumstances.

Two reasons, and either alone would be sufficient. The anti-slip property of expanded metal comes from the raised strand edges biting through whatever is on the surface; flattening removes those edges and leaves a smooth face that is genuinely slippery when wet. And the stiffness that lets an expanded panel span between supports comes largely from the strands' out-of-plane geometry, which flattening also removes.

A flattened panel used as flooring is therefore both more slippery and more flexible than the material the load tables were written for. Published capacities for expanded metal grating apply to the standard raised form.

Where a flat walking surface is genuinely required, the correct products are perforated anti-slip plate, plank grating or chequered plate, all of which are designed and rated for the purpose.

No, and this catches people out when substituting one for the other late in a project.

The rolling operation stretches the panel, so a flattened sheet is longer than the standard sheet it was produced from - the diamonds elongate slightly along the direction of rolling. The overall thickness drops substantially, since the strands no longer stand proud. And the strand thickness itself is altered by the rolls, so the figure quoted for flattened material is the finished thickness rather than the parent gauge.

The openings therefore change proportion a little too, which matters if the panel is doing any screening or if the appearance depends on the diamond proportions.

Specify from the flattened product's own data rather than assuming it matches the standard equivalent, and if a design is changed from standard to flattened part way through, re-check the panel size, the opening dimensions and the support centres.

Applications where the panel is seen, handled or mounted flush.

Architectural and interior work is the largest group: facade and screen panels, ceiling and bulkhead panels, room dividers, balustrade infill, feature walls and solar shading, where the flat face and regular mesh give a considered appearance and panels sit properly in their frames.

It is widely used in furniture, shopfitting and retail display, in cabinet and enclosure doors, and in shelving and basket products where a smooth surface avoids catching on goods.

Industrially it appears as filter and separator elements, as a substrate for coatings and laminates where flatness is required, and in guarding where the panel must sit tight against a frame.

It is not used for walkways, stair treads, platform infill, render lath, or anywhere the raised strand's grip or stiffness is the reason expanded metal was chosen in the first place.

Yes - it is standard expanded metal plus an additional manufacturing operation, and the price reflects that.

The panel is expanded first, exactly as standard material is, and then passed through a cold rolling mill in a separate pass. That means extra handling, extra machine time and extra process control, since the rolling has to be consistent across the panel or the flatness and dimensions vary.

The premium is generally modest relative to the total installed cost of an architectural or furniture application, where the panel is a visible component and the alternative would be a more expensive product altogether. It is significant on large-area functional work, which is one reason standard material dominates guarding, fencing and infill.

The question worth asking is whether the application truly needs a flat face. If the panel is not seen and not mounted flush, standard material does the job for less.