- Density
- About 720 kg/m³
- Stability
- High
- Relative cost
- Low
- Target moisture
- About 5 to 10 percent as shipped, typical, depending on the mill and grade
Materials / Panel
MDF: Density, Grades, Emissions and How to Specify It
A dense, uniform panel made of wood fibers and resin. Flat, smooth and easy to route, so it is the standard base for painted doors, mouldings and CNC parts in dry interiors.
Medium density fiberboard is made by breaking wood down into fibers and mixing them with a synthetic resin and wax. The mix is then pressed into panels under heat. There is no grain, no knots and no direction, so MDF is flat, smooth and the same in every direction. It routes into clean profiles and paints to a uniform surface, which solid wood and plywood do not do as well.
Buyers use it for painted cabinet doors, routed one-piece doors, mouldings and skirting, furniture case parts, store fixtures and as a substrate for veneer, laminate and foil. It costs less than plywood and solid wood, but it is heavier, weak at the edges and sensitive to water.
MDF is not one product. Density, the resin system, moisture resistance, fire performance and formaldehyde emissions all vary by grade and mill. Standard MDF, moisture resistant MDF, fire rated MDF and HDF are different panels at different prices. Name the grade, the thickness and the emission class in the RFQ.
Properties
| Density | About 650 to 800 kg/m³ for standard MDF, typical. Faces are denser than the core. HDF is about 800 kg/m³ and above. |
| Typical thicknesses | 3, 6, 9, 12, 15, 18, 22, 25 and 30 mm. Thin MDF is generally 8 mm and under. |
| Sheet sizes | 1220 x 2440 mm typical. Also 1830 x 2440 mm, 1525 x 2440 mm and longer lengths by order. |
| Emission classes | TSCA Title VI and CARB Phase 2 (US, 0.11 ppm for MDF and 0.13 ppm for thin MDF), E1 or E0 (EU and Asia), F4-star (Japan). NAF and ULEF options exist. |
| Screw holding | Fair in the face, weak in the edge. Edge screws can split the panel without pilot holes and correct spacing. |
| Moisture behavior | Swells in thickness when wet and does not recover. Edges and cut faces swell most. Moisture resistant grades swell less but are not waterproof. |
| Thickness tolerance | Sanded panels are held close, often within a few tenths of a millimeter. Ask for the stated tolerance. |
Typical published values for wood at about 12 percent moisture. Individual boards and panels vary.
Grades and classes
Face quality, core and emission class change the price more than thickness does. Name them on the RFQ.
- Standard MDFGeneral purpose interior grade for dry conditions. Covered by EN 622-5 in Europe and ANSI A208.2 in North America.
- Moisture resistant MDF (MR, MDF.H)Made with more resin or a moisture resistant resin. Lower thickness swell. Often dyed green, though color codes vary by mill. For kitchens and bathrooms, not for outdoor use.
- Fire rated MDF (FR)Treated to meet a fire class such as Euroclass B-s1,d0 or US Class A flame spread. Often dyed red or pink. Ask for the test report for your market.
- HDFHigh density fiberboard, about 800 kg/m³ and above, usually thin. Used for drawer bottoms, cabinet backs, door skins and flooring cores.
- Light MDFLower density panel, lighter to handle. Weaker in screw holding and edge profiles. Used where weight matters more than strength.
- Prefinished MDFMDF faced with melamine, veneer, foil or primer at the mill. Saves a finishing step. Name the face, color and gloss level.
Where MDF works
Products and parts where it earns its price, and where another material is the better buy.
Painted cabinet doors
One-piece routed doors and five-piece doors with MDF panels. Paints flat with no grain.
Mouldings and skirting
Primed paint grade profiles for interior trim. Lower cost than solid wood.
Furniture case parts
Tops, sides and shelves under veneer, laminate or paint.
CNC routed parts
Carved panels, signs, displays and routed decorative fronts.
Store fixtures and displays
Painted or laminated parts for retail interiors, often in fire rated grades.
Substrate for veneer and foil
Flat, uniform base for veneered panels and thermofoil doors.
Where it is a poor fit
- Outdoor use and wet areas without full sealing. Even moisture resistant MDF swells if water reaches the edges.
- Parts that rely on edge screws for strength, such as heavy shelf supports, without dowels, inserts or confirmat screws.
- Long unsupported shelves. MDF sags under load over time more than plywood of the same thickness.
In the factory
How MDF behaves in machining, gluing, finishing and drying. These points explain most price and quality differences between quotes.
- MachiningRoutes cleanly with carbide or diamond tooling. Cutting creates fine dust, so extraction is needed. The softer core shows on deep profiles.
- Edge sealingCut edges and routed profiles soak up paint. Seal them with a sanding sealer or edge primer before topcoat.
- FasteningUse pilot holes, confirmat screws, dowels or threaded inserts. Keep edge screws away from corners and ends.
- FinishingPaints, laminates, veneers and foils well. Sand faces lightly only, since the dense face layer is thin.
At each process step
- 05CNC routingMachines cleanly in every direction and takes routed profiles well. Produces fine dust and wears carbide quickly, so diamond tooling is common on long runs.
- 08Veneering and pressingThe flattest core for veneer. Faces telegraph very little. Heavy, and edges need lipping or banding.
- 10Sanding and finishingSmooth faces paint well. Edges soak up coating and need sealing and extra sanding before the topcoat.
- 11Inspection and packingEdges and corners crush easily and swell if wet. Corner protectors and film wrap are essential.
How to specify MDF
Example RFQ lines you can adapt.
- MDF, standard grade, 18 mm, density about 720 kg/m³, TSCA Title VI compliant and CARB Phase 2 labeled.
- Moisture resistant MDF for kitchen doors, 18 mm, E1 or better, edges sealed before painting.
- Fire rated MDF for store fixtures, Euroclass B-s1,d0 test report supplied, 18 mm.
What to check on samples
Approve one sample in writing and keep it as the reference for every shipment.
- Measured thickness and flatness against your stated tolerance
- Edge quality on routed profiles after sealing and painting
- Emission certificate and label matching the panel grade and mill
- Screw holding on sample parts using your actual hardware
- Thickness swell on a water soak test for moisture resistant grades
- Fire test report for fire rated grades, matched to the panel thickness
Alternatives to MDF
When price, supply or the use case points elsewhere.
- PlywoodLighter and stronger, with better screw holding at the edges. Costs more and does not paint as flat.
- ParticleboardLower cost for melamine faced case parts. Coarser core, so it does not route or paint like MDF.
- PoplarSolid wood for painted frames and parts that need edge strength and screw holding.
Products often made in MDF: table tops and countertops, cabinet doors and fronts, panels and veneer, millwork and mouldings, CNC routed parts, wood packaging and boxes.
Product lines in MDF: RTA furniture kits, desk tops, Shaker cabinet doors, primed finger-jointed mouldings, wood slat wall panels, retail display fixtures, wooden wine boxes.
Questions about MDF
Related guides:
- MDF vs Plywood vs Particleboard: Choosing a Panel for Wood Products
- Compliance Rules That Apply to Manufactured Wood Products
- CNC Routing for Wood Parts: What Drives Tolerance and Price
Reference: Wikipedia: Medium-density fiberboard
Is MDF stronger than particleboard?
MDF is denser and more uniform, so it routes, paints and holds face screws better. Both are weak at the edges compared with plywood.
Is moisture resistant MDF waterproof?
No. It swells less than standard MDF in humid conditions and short contact with water, but it is not made for outdoor use or standing water. Seal all edges.
What is the formaldehyde limit for MDF in the US?
Under TSCA Title VI the limit is 0.11 ppm for MDF and 0.13 ppm for thin MDF, the same as CARB Phase 2. Panels must be certified by an approved third party, and finished goods must be labeled.
What is the difference between MDF and HDF?
HDF is pressed to a higher density, about 800 kg/m³ and above. It is harder and usually thin, used for drawer bottoms, cabinet backs, door skins and flooring cores.
Why do screws pull out of MDF edges?
The core is softer than the faces and the fibers split around a screw. Use pilot holes, special panel screws, dowels or inserts, and keep fasteners away from ends.
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