# Metal mesh

Woven, welded and expanded mesh: opening geometry, material identity, edge condition and application limits.

Reviewed: 2026-11-01

Tags: materials, stock-forms, mesh, screening

## Identify the construction first

Haver & Boecker's **2024** square-aperture table lists two **6.30 mm clear openings**. With **1.25 mm wire**, it gives **70% open area and 2.80 kg/m²**. With **2.00 mm wire**, it gives **58% and 6.51 kg/m²**. Specify wire size and opening together, then account for supports covering part of the screen. [Haver & Boecker industrial-screen table](https://www.haverboecker.com/fileadmin/HaverBoecker/DieDrahtweber/03_documents/01_pdf/Industriesiebe/Inustriesiebe-Hauptsorten_en.pdf)

Metal mesh is an open material form, not a single specification. Woven wire cloth, welded wire grids and expanded sheet can all be described commercially as mesh, but their construction, dimensional conventions and acceptance requirements differ. Record the construction before comparing an opening size or a price per square meter.

| Construction | What must be identified |
|---|---|
| Woven wire | Weave, openings or count, wire diameters and direction, alloy and edge treatment. |
| Welded wire | Wire sizes, clear or center-to-center spacing, weld requirements and panel edges. |
| Expanded metal | Raised/flattened type, diamond direction, strand geometry and sheet dimensions. |

ASTM's public **E2016-22** scope covers general industrial woven wire cloth, including particle separation. It expressly excludes welded cloth, test-sieve cloth, galvanized hardware cloth and special filter/Dutch cloth, among other products. Its tolerance and delivery provisions therefore should not be copied onto every item called mesh. The specification identifies inch-pound values as standard, with SI conversions informational. [ASTM E2016-22](https://store.astm.org/e2016-22.html)

## Woven geometry and mesh count

For regular open square cloth, the clear opening lies between adjacent wires; pitch includes one opening and one wire diameter. A mesh count needs a length basis and must be accompanied by wire diameter. A count stated without units or weave is not a complete opening specification. The wovenwire.com technical reference gives the opening relation **a = 1/M − d** when M is count per inch and d is wire diameter in inches. No technical revision date was verified on that page. [Wire-cloth opening formula](https://wovenwire.com/reference/wire-cloth-opening-formula.htm)

Rectangular cloth requires two directional descriptions. Do not silently exchange warp and weft or reduce an elongated aperture to one “mesh size.” For a non-square weave, request the supplier's full dimensional definition rather than extending the square formula.

**Illustrative geometric calculation:** assume ideal square cloth with 10 openings per inch and 0.025-inch round wire. Pitch is 0.100 inch; clear opening is 0.075 inch, or 1.905 mm. Ideal projected open fraction is (0.075 / 0.100)² = **56.25%**. This calculation assumes a regular planar projection, excludes edges and supports, and is not a tolerance or a filtration rating. Increasing wire diameter while retaining count reduces the opening and projected open area.

## A bounded manufacturer comparison

Haver & Boecker's *Main Specifications of Industrial Wire Screens*, with **printed copyright 2024**, provides a practical example of the tradeoff. Its square-aperture table lists:

| Clear aperture | Wire diameter | Listed mass | Listed open screening area |
|---|---:|---:|---:|
| 6.30 mm | 1.25 mm | 2.80 kg/m² | 70% |
| 6.30 mm | 2.00 mm | 6.51 kg/m² | 58% |

The same aperture therefore does not establish equal mass or open area. These are specific manufacturer table rows, not a universal mass formula or a proof of strength. [Haver & Boecker, industrial-screen specifications](https://www.haverboecker.com/fileadmin/HaverBoecker/DieDrahtweber/03_documents/01_pdf/Industriesiebe/Inustriesiebe-Hauptsorten_en.pdf)

For an assumed 2.0 m² of the listed cloth, multiplying gives 5.60 kg or 13.02 kg before framing, trimming and other additions. Nominal screening area is not the same as the complete assembly's unobstructed area: supports and clamping can cover part of the cloth.

## Welded-wire conventions

Banker Wire distinguishes **center-to-center spacing** from **clear opening** and recommends decimal wire diameter rather than gauge for accuracy. It also distinguishes trimmed and untrimmed edges and describes weld-set-down as a reduction in the combined thickness of intersecting wires during welding. Its webpage has no verified issue date. [Banker Wire, welded-wire basics](https://www.bankerwire.com/welded-wire-mesh/welded-wire-basics/)

An assumed 25 mm center spacing with 3 mm wires gives a nominal 22 mm clear gap in a regular grid. A purchase description saying only “25 mm mesh” could therefore be ambiguous by 3 mm before tolerances are considered. Specify the reference points, both directions and wire diameters.

When the panel carries load, specify weld acceptance and support details rather than inferring capacity from the base wire alone. Include edge overhang and attachment geometry: a cut panel may have projecting wire ends, and its border may not terminate at the same place as a full repeating cell.

## Expanded-metal conventions

McNICHOLS describes expanded metal as sheet that is slit and stretched, supplied in **standard/raised** and **flattened** forms. Its ordering guidance separates pattern direction, open area, material, sheet size, finish and shearing preference. The Long Way of Design commonly follows sheet length for its inventory, but that is a supplier convention to verify, not a universal orientation rule. No issue date was verified on the webpage. [McNICHOLS standard expanded metal](https://www.mcnichols.com/expanded-metal/standard)

Its **2018 master catalogue**, identified by printed copyright, separately labels **SWD/LWD** as design dimensions and **SWO/LWO** as opening dimensions. Do not substitute one pair for the other when specifying clearance. It also illustrates bond and random shearing arrangements; edge termination belongs in the fabrication description. [McNICHOLS 2018 catalogue, expanded-metal diagrams](https://assets.mcnichols.com/content/dam/mcnichols/catalogs/McNICHOLS_MasterCatalog_2018.pdf)

Raised and flattened descriptions alone do not establish overall thickness, strand size or a permissible span. Retain the exact style and supplier drawing when checking fits and framing.

## Application qualification and receiving

Treat projected open area as a geometric descriptor. It does not alone establish airflow pressure loss, separation efficiency, cleanability, acoustic performance or load capacity. For filtration, define the fluid, particles, pressure differential, support arrangement and required performance test. For guards or walking surfaces, obtain acceptance for the complete supported assembly; a nominal opening or catalogue application label is insufficient.

Before accepting substitution:

1. Match construction, directional geometry, alloy and finish.
2. Identify the governing specification, edition and agreed tolerances.
3. Confirm panel/roll dimensions, cut direction, edge treatment and attachment.
4. Verify performance against the actual duty and support conditions.
5. Inspect the agreed characteristics and preserve lot identity through fabrication.

Record count, pitch, clear opening and open area separately, with units and the drawing or table revision.

## Related reference

[Stock forms and dimensions](index.md)