MDF (medium-density fibreboard) is an engineered board made from wood fibres bonded with resin under heat and pressure. Density is typically 700–800 kg/m³ — higher than particleboard — which gives it a uniform core, a smooth machined edge and good screw holding along the face.
What the density buys you
The fibre structure is uniform in every direction, so MDF routes, profiles and paints cleanly. That is why shaker door panels, moulded edges and curved fronts are usually MDF rather than particleboard — the machined profile holds its shape without chipping out.
The same density makes it heavy: an 18 mm sheet is roughly 13–15 kg/m², about 10–15% heavier than particleboard of the same thickness. On a container shipment that difference is real, and it is why MDF is used selectively rather than throughout.
| Property | MDF | Particleboard |
|---|---|---|
| Density | 700–800 kg/m³ | 650–750 kg/m³ |
| Machined edge | Clean, holds profile | Chips, needs banding |
| Screw holding, face | Good | Good |
| Screw holding, edge | Moderate | Weak |
| Water resistance | Poor unless MR grade | Poor unless MR grade |
| Relative cost | Higher | Lower |
The water problem
Standard MDF swells when water reaches the core, and it does not return to thickness when it dries. A 24-hour soak can produce 8–15% thickness swelling, and the panel stays swollen. There is no repair — the board has to be replaced.
Moisture-resistant MDF (MR MDF) uses a different resin and typically swells far less, but it is still not waterproof. For laundry, bathroom and coastal work, the correct answer is MR board with sealed edges and no standing water, not "MDF is fine".
What to write on the purchase order
"MDF" alone tells a factory almost nothing. Specify the grade (standard or MR), the thickness (16 or 18 mm), the density range, and the formaldehyde class (E0, E1 or CARB P2 depending on market). A supplier quoting "MDF" without a grade is quoting the cheapest board that fits the words.
For painted doors, also specify the face: MDF takes two-pack lacquer directly, but a sealed primer coat is what stops the edge grain from telegraphing through the finish after six months.
Frequently asked questions
Is MDF better than particleboard for cabinets?
For machined and painted components, yes — cleaner edge, better profile, flatter face. For carcass panels where cost and weight matter, particleboard is usually adequate. Many kitchens use both: MDF doors on particleboard boxes.
Does MDF hold screws well?
Along the face, yes. Into the edge, only moderately — an edge screw in MDF strips more easily than in plywood. For hinges and cam fittings, specify the correct insert or use a dowelled joint.
Is MR MDF waterproof?
No. It resists moisture better than standard MDF but still swells if water sits on an unsealed edge. It is a margin of safety, not a waterproof board.
What formaldehyde class should I ask for?
E1 as the minimum for most markets, E0 where the project specifies it, and CARB P2 for the United States. Ask for the test report for the specific board, not a generic factory certificate.
