MDF (Medium Density Fibreboard) is the masterpiece of timber reconstruction. While OSB exploits visible flakes, MDF pulverises wood to a molecular level, then thermally re-aggregates it into a panel with a silky surface.
Wood chips are fed into a thermo-mechanical defibrator: high-pressure steam shreds the wood, separating lignin from cellulose. These fibres are sprayed with synthetic resins (MUF or PMDI) and water-repellent paraffin, forming a soft mat that enters high-temperature presses. The heat cures the resin and plasticises the natural lignin, creating a solid board with a silky surface.
Unlike solid wood, MDF has no grain (isotropic material). This absence of directionality makes it the material of choice for CNC milling: it can be carved and engraved in 3D, producing smooth, compact edges. The HDF (High Density) variants or those coloured throughout (e.g. Valchromat) offer monolithic architectural finishes.
Standards
European and international references applicable.
Physical properties
Usage environment
Use MDF.H (green, hydrophobic) in damp environments. For acoustic applications prefer HDF (> 800 kg/m3) thanks to its high specific mass. For interior design specify NAF (No Added Formaldehyde) panels with PMDI or soy-based glues. Always seal cut edges in humid environments.