Example data mode. The sample companies, offers and requests shown here are fictional (AI pictures) and are not counted in the figures below.
Lesson 6 of 7
Hardwood grading: oak, beech, ash and colour defects
A softwood mill sells volume to a specification. A hardwood mill sells appearance, and the value gap between outcomes is far larger: the same oak log can become furniture boards, flooring lamellas or pallet timber. This lesson covers how European hardwood boards are graded, which colour defects matter, and how the American system differs.
Which standard covers what
EN 975-1 covers appearance grading of sawn oak and beech (the April 2009 edition is current per AFNOR). EN 1316-1 classes oak and beech round timber A to D (2012 edition), and EN 1316-3 covers ash, maples and sycamore as round timber only. EN 975-2 (poplar) is known by title only. These texts are paywalled and were not read.
No opened source shows a European sawn appearance standard for ash, maple or sycamore, so those boards are typically traded by agreement.
The oak grade codes, as a supplier describes them
A UK supplier guide (EcoChoice, undated) describes the code: Q for Quercus, a product letter (S, B, F or P), then A (exceptional), 1 (good) down to 4 (poor), with X or XX for sapwood on one or both faces. For the F grades:
| Grade | Knot criterion (supplier page) | Wane |
|---|---|---|
| QF3 | Sound knots under 10 mm disregarded; up to 3 knots no larger than 40 mm; one dead knot under 20 mm | under 3 mm |
| QF4 | Sound knots under 70 mm; two dead or unsound knots (under 20 mm and under 35 mm) | under 10% of width, 20% of length |
This is a commercial summary of a paywalled standard; some values on the page were illegible and shakes are not covered. Use it for orientation only. The same page says a selected lot may contain no more than 10% of boards below the specified grade.
Boules. The supplier summary states that in a boule (a log sawn through and through and sold in log sequence) at least 65% must be the specified grade, under 25% may be one grade lower and under 10% two grades lower. Worked example. For a boule of 40 boards, 65% is 26 boards, 25% is 10 (so at most 9) and 10% is 4 (so at most 3). Check these against the standard before writing them into a contract.
The UK commentary Making the Grade (Forest Research, 2005) simplifies EN 975-1 to three grades: 1 (uniform, "clear" or "prime"), 2 (some knots or splits, usable areas clear) and 3 (any knots, splits and colour variation, subject to suitability).
German customs and the American contrast
The German trade customs (Tegernseer Gebraeuche, 2023) have no hardwood grade classes: hardwood must meet the agreed grades, and without an agreement it must be dimensionally stable at a reference moisture of 18%.
NHLA grades are yield-based. According to the American Hardwood Export Council, FAS needs boards at least 6 in. wide and 8 ft long with 83 1/3% to 100% clear yield; No. 1 Common needs 3 in. by 4 ft with 66 2/3% up to 83 1/3%. NHLA promises a share of clear wood, which suits cutting-to-size industries; EN 975-1 describes what the face may show, which suits users of whole boards. Neither describes strength. Mixing the two vocabularies in one order is a classic source of disputes, and no open conversion table exists.
Colour and heart defects
Beech red heart (false heartwood) is a coloured core, not decay in itself but often accompanied by it. A 2010 Romanian study (Campu; nine trees, 65.638 m3) found red heart in about 34% of the volume, about 22.3 m3 (own calculation), varying from 5% to 48% between logs. Under EN 1316-1:2001 no wood reached class A and only about 5% reached class B; the author estimates that downgrading cut beech round wood revenue by 40 to 50%. It is a small sample from one felling area and shows the mechanism, not a European average.
Steaming homogenises colour. In Slovak laboratory blanks (Dzurenda and Dudiak, 2024), steaming at about 95 degrees C for up to 24 h cut the sapwood-heartwood contrast from 14.8 to 5.5, a fall of 63% (own calculation), but higher temperatures gave a darker board. Uniformity is traded against darkness.
Oak sapwood is treated explicitly in the grade code (X, XX). Ash forms a facultative brown heart, usually at 60 to 80 years, which does not affect strength but is mostly rejected for fitting-out wood (Bavarian Merkblatt). In a Croatian study of narrow-leaved ash, dead trees in the 62.5 cm class were worth 59.76 EUR/m3 against 183.25 EUR/m3 for trees with 61 to 80% defoliation, about one third (own calculation).
Key points
- EN 975-1 (oak, beech) describes what the face may show; NHLA grades by share of clear cuttings; neither describes strength.
- No opened source shows a European sawn appearance standard for ash, maple or sycamore; trade is by agreement.
- Oak criteria here come from a supplier summary and a UK commentary, not the standard; verify before using them in a contract.
- In a boule, the supplier summary states at least 65% specified grade, under 25% one grade lower and under 10% two lower.
- Red heart in beech and brown heart in ash are colour defects, not strength defects, and can cut value sharply.