Hardboard
ASTM ANSI A135.4 · EN 622-2 · JIS A5905
Hardboard is a high-density fibreboard consolidated from refined wood fibre under high heat and pressure, specified to EN 622-2, ANSI A135.4, JIS A5905 and GB/T 15102 in service, standard, HB.H and tempered (oil-treated) conditions.
Reference datasheet — Hardboard is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Hardboard tempers and conditions
Hardboard is supplied in 2 conditions, soft to hard.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Service | Cheapest grade for non-structural backs, pegboard and packaging where only a smooth face is needed. | 12 | 0.9 | 0.13 W/m·K | ||
Hardboard for humid conditions | Pick when the panel sees intermittent humidity (bathroom/utility interiors, protected exterior soffits). | 22 | 1 | 0.16 W/m·K |
Supply forms, finishes and certifications
Ways Hardboard is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
TEMP | Tempered | Surface finish |
STDDefault | Standard | Standard supply |
What is Hardboard?
Hardboard is a high-density fibreboard consolidated from refined wood fibre under high heat and pressure, specified to EN 622-2, ANSI A135.4, JIS A5905 and GB/T 15102 in service, standard, HB.H and tempered (oil-treated) conditions. It is used in thin gauges wherever a smooth, hard, low-cost skin is needed, with about 20 MPa tensile strength, 4.2 GPa modulus, 1% elongation and the highest density in the panel family at 0.95 g/cm3. Maximum service temperature is 80 C and the corrosion/decay score is 30, so raw edges and the back face swell if left unsealed. Machinability score is 70 and the silica-bearing dust is abrasive; plywood is the alternative when fastener holding at the edge is required. Hardboard has a density of 0.95 g/cm³ (0.0343 lb/in³), heavier than 77% of natural material grades. Hardboard has a tensile strength of 20 MPa (2.9 ksi), weaker than 51% of natural material grades. Elongation at break is 1% and the elastic modulus is 4.2 GPa (0.609 Msi).
What is Hardboard used for?
- Cabinet backs
- Door skins
- Laminate flooring core
- Pegboard
- Packaging
Advantages
- Tough — resists crack growth — 0.7 MPa·√m (0.637 ksi·√in), better than 78% of natural material grades
Limitations
- Hard to polish — 25/100, worse than 80% of natural material grades
- Heavy — 0.95 g/cm³ (0.0343 lb/in³), worse than 77% of natural material grades
- Needs corrosion protection — 30/100, worse than 77% of natural material grades
- High embodied carbon — 0.85 kg CO₂/kg, worse than 76% of natural material grades
Hardboard properties
Typical room-temperature values; bars are the position among natural material grades.
Physical2
Hardboard has a density of 0.95 g/cm³ (0.0343 lb/in³), heavier than 77% of natural material grades.
Mechanical9
Hardboard has a tensile strength of 20 MPa (2.9 ksi), weaker than 51% of natural material grades. Elongation at break is 1% and the elastic modulus is 4.2 GPa (0.609 Msi).
Thermal5
Hardboard is rated for continuous service to 80°C (176 °F). It conducts heat at 0.15 W/m·K (0.0867 BTU/hr·ft·°F), better than 52% of natural material grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
Hardboard is an electrical insulator with a dielectric strength of 2 kV/mm (50.8 V/mil) and a resistivity of 1×10⁷ Ω·m.
Chemical & Environmental1
Corrosion resistance is poor (30/100), worse than 77% of natural material grades.
Sustainability4
Producing a kilogram of Hardboard takes about 16 MJ of energy and emits 0.85 kg of CO₂ — more than 79% of natural material grades. Typical recycled content is 85%.
Manufacturability2
Hardboard's machinability is very good (70/100, worse than 67% of natural material grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Working with Hardboard
Is Hardboard easy to machine?
Cuts, routs and laser-cuts cleanly with carbide or diamond tooling; the silica-bearing dust is very abrasive, so expect short HSS tool life and use downcut bits plus dust extraction to avoid face chipping.
Can Hardboard be welded?
Not weldable — joined by PVA/urea or hot-melt adhesive, staples, or clinched fasteners into a frame; edge screws split the board.
Can Hardboard be formed, bent or molded?
Can be cold-bent to modest radii in thin gauges (2–4 mm) and formed to tighter radii after water soaking with subsequent drying under restraint; hot pressing during manufacture also allows embossed/perforated (pegboard) profiles.
Hardboard chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| lignin (self-bonding, part of fibre)fraction of the fibre itself; primary binder in wet-process board | 20 – 30 | 25 |
| phenol-formaldehyde resinadded binder; higher in dry-process and HB.H grades | 0 – 2.5 | 1 |
| paraffin wax / sizingwater repellent | 0.3 – 1.5 | 0.8 |
| drying oil (linseed/tall oil)1–6 % only in tempered grade, polymerised by heat treatment | 0 – 6 | 0 |
| moistureequilibrium MC as shipped | 4 – 9 | 6.5 |
| wood fibre (lignocellulose)steam-refined softwood/hardwood chips or recovered wood | ≥ 92 (balance) |
What surface finishes work on Hardboard?
Smooth S1S face takes primer and paint directly; sand and seal the porous back and all cut edges, since raw edges swell and fuzz — tempered board needs a light scuff sand or a shellac/oil-block primer for good paint adhesion.
Equivalent designations
Standards and trade names that resolve to Hardboard in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- ANSI A135.4
- EN / DIN / Werkstoff-Nr.
- 622-2
- JIS
- A5905
- Similar grades
- GB/T 15102
How much does Hardboard cost?
Hardboard is a budget-cost natural material ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Hardboard — frequently asked
What is Hardboard used for?
Hardboard is typically used for cabinet backs, door skins, laminate flooring core, pegboard and packaging. In short: densest engineered wood panel; smooth paint-ready face; thin-gauge cold-bendable skin.
What is the tensile strength of Hardboard?
Hardboard has a typical tensile strength of 20 MPa (2.9 ksi) — weaker than 51% of natural material grades. Strength varies by condition: see the 2 listed tempers.
Is Hardboard easy to machine?
Yes — machinability is rated very good (70/100, worse than 67% of natural material grades). Cuts, routs and laser-cuts cleanly with carbide or diamond tooling; the silica-bearing dust is very abrasive, so expect short HSS tool life and use downcut bits plus dust extraction to avoid face chipping.
Can Hardboard be welded?
Not weldable — joined by PVA/urea or hot-melt adhesive, staples, or clinched fasteners into a frame; edge screws split the board.
What surface finishes work on Hardboard?
Smooth S1S face takes primer and paint directly; sand and seal the porous back and all cut edges, since raw edges swell and fuzz — tempered board needs a light scuff sand or a shellac/oil-block primer for good paint adhesion.
Can Hardboard be formed, bent or molded?
Can be cold-bent to modest radii in thin gauges (2–4 mm) and formed to tighter radii after water soaking with subsequent drying under restraint; hot pressing during manufacture also allows embossed/perforated (pegboard) profiles.
What is the maximum service temperature of Hardboard?
Hardboard is rated for continuous use to about 80°C (176 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Hardboard cost?
Hardboard is a budget-cost natural material ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 622-2 Fibreboards — Specifications — Requirements for hardboards — CEN (2004)
- ANSI A135.4 Basic Hardboard — Composite Panel Association / ANSI (2012)
- JIS A 5905 Fibreboards — JISC (2014)
- Wood Handbook — Wood as an Engineering Material, Ch. 11 Wood-Based Composite Materials — USDA Forest Products Laboratory (2021)
- Inventory of Carbon & Energy (ICE) v3 — fibreboard/hardboard — Circular Ecology (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.