MDF — medium density fibreboard — is a panel made from finely ground wood fibres bonded with resin and pressed under heat and pressure into a homogeneous board. Unlike plywood or chipboard it has no plies and no flakes, just one even structure, which is exactly why its faces are so smooth and its edges machine so crisply.
Properties and uses
Density is typically 600 to 800 kg/m³, making MDF heavier than chipboard of the same thickness. Common thicknesses run from 3 mm up to around 38 mm. The board barely moves across its width, is dimensionally stable, and has no grain or knots.
Typical uses: painted cupboards and fitted furniture, skirtings and mouldings, door panels, wall panelling, kitchen fronts, ceiling elements, and pattern or one-off mould making.
Points to watch
- Not moisture resistant. Standard MDF swells irreversibly once wet. In a bathroom or kitchen run use moisture-resistant MDF (often dyed green) — and even that is not an exterior board
- Edges drink paint. Cut edges are porous. Seal them with edge filler or an extra coat of primer, or the edge will still look dull and rough after two coats of paint
- Pilot holes. Never screw into an end edge without drilling first: the board splits. Pre-drill and use long, slim screws — or better still dowels or biscuits
- The dust is harmful. Sawing and sanding release very fine wood dust carrying resin residues. Use extraction and wear at least a P2 mask
- Formaldehyde. For interior work choose boards with a low emission class (E1 or better)
- Deflection. MDF is less stiff than plywood. Support 18 mm shelves at spans over roughly 600 to 700 mm or they will sag in time
- Not structural. Do not use MDF as load-bearing or racking sheathing; plywood and OSB are the boards for that
Related terms
- Sheet materials
- Plywood
- OSB
- Hardboard
- Wood glue
- Mouldings
- Fitted cupboard
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