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Overview and range in Europe

European (common, English, Persian) walnut, Juglans regia, is grown mainly for its nuts, and timber is largely a by-product. The Bavarian LWF Merkblatt 60 calls it a noble broadleaf valued for centuries as a luxury wood, often named the most valuable domestic timber, but says it has never been part of managed forestry; breeding material and silvicultural trials began only in the last 20 years before that text. Single trees stand in gardens, parks, farmland and avenues, and Europe's largest walnut stands are nut plantations in the Dordogne and near Grenoble in France.

Where it is native is unclear. EUFORGEN says the native range is hard to pin down because of long cultivation, with conflicting origin points in the Mediterranean, central Asia and South Asia. It reports glacial refugia in the Balkans, Greece, Turkey and around the Caspian and Black Sea, and human spread along trade routes. Forest Research (Great Britain) says native to south-eastern Europe and Asia, east to China; the Pirinoble handbook (CTFC, Catalonia) says Central Asia; Gabarro (Spain) says south-east Europe, west Asia, north-west India and the Himalaya.

Site demands, from Forest Research (Britain): rainfall of 700-1000 mm well distributed through the year, medium to very rich fresh to moist soils (alkaline soils with good rooting depth are fine), sunny sheltered sites, and no frost pockets, exposure or shade. It is light-demanding and intolerant of competition. Forest Research gives a 60-80 year rotation ending at under 100 trees per hectare of 40 cm or more. The Pirinoble handbook, which mainly models a walnut hybrid (J. x intermedia) in the Pyrenean area, gives a final cut at 50-60 years with a target of about 60 cm breast-height diameter at 60 trees per hectare, and says common J. regia is more sensitive to water stagnation and spring frost and tends to form leaning stems in forest conditions. Armillaria root rot is the main hazard named by Forest Research; Pirinoble adds Phytophthora and bark spots (Brenneria nigrifluens) that can devalue timber.

Appearance and identification

LWF Merkblatt 60 gives sapwood 5-10 cm wide, grey-white to reddish-white. Heartwood varies with age and site from light grey and mouse-grey to dark brown or blackish-brown, often striped, irregularly veined or cloudy. Tropix (CIRAD) describes brown heartwood, yellow-brown to pinkish-brown, sometimes greyish, often with darker veins; medium texture; straight to wavy grain with no interlocked grain; sapwood not clearly demarcated (this conflicts with LWF's wide sapwood band, so I take the LWF width as the practical figure for sawn boards).

The wood is semi-ring-porous: large earlywood vessels, smaller latewood vessels, clear growth rings, and heartwood vessels often plugged with silvery tyloses (LWF). Rays are fine and give narrow dark radial flecks. Lustre is low and fresh wood has a faint, sour odour. LWF says dark, black-striped Caucasian walnut was most prized until the 1930s, whereas an even, light grey-brown French type is preferred today.

Two cautions. LWF warns that many substitute woods are sold under misleading "walnut" names (dibetou, mutenye, mansonia, paldao, sweet gum, aningeria). And American black walnut (Juglans nigra) is similar in colour and figure; LWF does not say how to separate them, and I found no source that does.

Properties that matter

Figures below are labelled by species and region. J. nigra is American and shown only for contrast; Wood Database lists J. regia ("English walnut") under distribution "Eastern Europe and western Asia" but does not state where its specimens grew.

Property	Value	Source	Region / species
Density, mean rN	0.68 g/cm3 ("medium-heavy")	LWF Merkblatt 60	Bavaria, Germany; J. regia. Moisture basis not restated in my extract
Density at 12%	650 kg/m3	Gabarro encyclopedia	Spain; J. regia
Density at 12%	640 kg/m3 (SG 0.64 at 12%)	Wood Database	Origin not stated; J. regia
Specific gravity at 12%	0.66 (label inferred from garbled PDF)	Tropix datasheet	France (CIRAD); J. regia
Shrinkage green to oven-dry, L / R / T / vol.	0.5 / 5.4 / 7.5 / 13.4-13.9%	LWF Merkblatt 60	Germany; J. regia
Shrinkage R / T / vol.; T/R	5.5 / 7.5 / 13.0%; 1.4	Wood Database	Origin not stated; J. regia
Shrinkage R / T (Tropix, same values, labels inferred)	5.5 / 7.5%	Tropix	France; J. regia
Modulus of elasticity	12,500 N/mm2 (LWF); 11,800 MPa (Tropix, inferred); 10.81 GPa (Wood Database)	LWF; Tropix; Wood Database	Germany; France; origin not stated
Bending strength	117 MPa (Tropix, inferred); MOR 111.5 MPa (Wood Database)	Tropix; Wood Database	France; origin not stated
Crushing strength	64 MPa (Tropix, inferred); 50.2 MPa (Wood Database)	as listed	France; origin not stated
Hardness	Brinell 119-147 N/mm2 long., 85-110 transverse (LWF); Janka 5,410 N (Wood Database)	as listed	Germany; origin not stated
Black walnut, density at 12%	610 kg/m3	Wood Database	North America (J. nigra)
Black walnut, Janka / MOR / MOE / crushing	4,490 N / 100.7 MPa / 11.59 GPa / 52.3 MPa	Wood Database	North America
Black walnut, shrinkage R / T / vol.	5.5 / 7.8 / 12.8%; T/R 1.4	Wood Database	North America

How to read it: all three J. regia sources place density at roughly 640-680 kg/m3, and shrinkage is moderate with a low T/R ratio (1.4-1.6), consistent with LWF's description of walnut as among the less-shrinking domestic woods that hold their shape once dry. Strength figures disagree more: crushing strength is 64 MPa in Tropix and 50.2 MPa in the Wood Database. LWF's bending strength entry of 58-72 N/mm2 sits far below the 111-117 MPa of the two other sources, and LWF itself notes that its table layout is garbled, so I treat that figure as unreliable and do not use it. Black walnut is lighter (610 kg/m3) and softer by Janka, so do not read American data as European.

LWF describes the wood as fine-grained, fairly hard and tough, with little splintering under dynamic load.

Sawing and log handling

LWF says walnut is easy to saw by hand and machine; Tropix recommends ordinary or alloy-steel sawteeth with a normal blunting effect, and rates peeling as good. I found no verified guidance on log storage or sawing patterns.

What drives value is the log. LWF reports that the most valuable sections are the lowest, bulb-like thickened parts at the stem-root transition, which extend into the soil: to get the burls, trees are dug up with the root stock rather than felled above ground. Burls are usually peeled eccentrically into burl veneers ("head veneers", Nussbaumkoepfe), and pyramid veneers from stem and branch forks are also prized. A mill receiving walnut logs should therefore ask how the butt was cut; the sources give no premium.

The Pirinoble handbook says the highest-quality logs go to veneer. Pirinoble targets a clean bole of 3-6 m; Forest Research advises pruning selected stems above 2.5 m. Sapwood is wide (5-10 cm, LWF), so sapwood share per log is a real yield and grade item. Iron contact on damp wood causes blue-black stains (LWF), a standard precaution for fresh boards.

Drying

Sources disagree. LWF says drying is generally unproblematic because of little tendency to check or crack, but slow, and kiln drying must be carefully controlled. Tropix rates the drying rate as normal to slow, with slight distortion risk, no casehardening risk, slight checking risk and a collapse entry listed as "yes", which the extraction marked as unusual. Gabarro states the opposite on speed: it dries "considerably fast", with a risk of collapse and casehardening. I cannot resolve this from the sources; treat collapse and casehardening as possible until your own trials show otherwise.

The only numeric schedule I read is the Tropix one, given for thickness of 38 mm or less:

Moisture content	Dry-bulb C	Wet-bulb C	RH %
Green	50	47	84
40%	50	45	75
30%	55	47	67
20%	70	55	47
15%	75	58	44

Tropix says to raise humidity by 5% at each step for 38-75 mm and by 10% above 75 mm, that it is for information only, and that it must follow the applicable code of practice. I did not test it and do not endorse it; given the conflicting collapse statements, it would need checking on a trial charge.

Steaming for colour is a walnut-specific topic, but my sources are about American black walnut and are not European data. A WOODWEB forum answer (2014, black walnut, anecdotal apart from one named adviser) describes steaming to darken white sapwood to match the heartwood: a European study cited there found 100 degrees C (212 F) at 100% relative humidity for 16 hours gave the most uniform colour, most of the change occurring in the first four hours; non-pressure steaming was typically 24-96 hours at 190-212 F; pressure-steamed lumber must cool in the vessel or it risks end checking and honeycomb; and steam should not be used in a dry kiln because of the corrosive volatiles. A 1980 paper (Chen and Workman, abstract only) found steaming time and temperature strongly change the colour of wood fluids. Whether the same applies to J. regia is untested in my sources.

Machining, gluing and finishing

LWF: easy to knife, peel, plane and profile; turns and carves excellently; bends well; nails and screws easily; glues without problems, although alkalis in glues can cause tannin stains. It polishes excellently, stains very well and accepts matt finishes and lacquers. Splitting is usually poor because of irregular grain. Tropix rates nailing and screwing as good and gluing as correct; Gabarro also warns that alkaline glues may cause difficulties. The Wood Database (J. regia page) says planer tearout can occur with irregular or figured grain.

The Wood Database lists walnut as a sensitizer (eye and skin irritation usual, severe reactions uncommon); I found no European occupational-health source. LWF reports low chemical reactivity.

Durability and treatment

Tropix gives the heartwood fungal class 3 (moderately durable), with dry-wood borers not a concern for heartwood, termites class S (susceptible) and use class 2 ensured by natural durability (inside or under cover, dampness possible), referencing NF EN 350-2. It adds that sapwood is always non-durable, that treatment is advisable under temporary humidification, and that permanent humidification is not recommended. LWF agrees: only moderately durable outdoors, heartwood resistant to furniture beetle and Lyctus, only sapwood at risk. The Wood Database J. regia page, however, says moderately durable but susceptible to insect attack, and rates black walnut "very durable"; the latter is an American species.

Treatability: Tropix puts heartwood in class 3 (poorly permeable), and says sapwood is permeable to preservatives. Gabarro says medium impregnation capacity in sapwood and low to none in heartwood.

Typical uses and market notes

Uses named by LWF and Tropix: high-class furniture and cabinetwork, sliced veneer, interior joinery, panelling, doors, turned goods, carving, marquetry, musical instruments (piano veneers and parts), and gunstocks (LWF: the best timber for rifle stocks). Sapwood is sometimes used as veneer, left pale or stained to match.

Market: LWF says walnut is scarce and expensive and has never been part of the commercial broadleaf trade; solid use is often replaced by substitutes. The Wood Database (a US source) says European walnut is "likely expensive", sometimes sold only as veneer, that nearly all lumber comes from cultivated trees, and that the IUCN rates the species near threatened. I did not find a current European price list, and LWF gives only a historical (1842) price, so I give no prices. Pirinoble's cash-flow model (2013 euro) is for hybrid walnut and is not a market price.

What is uncertain or varies

• Native range, and so "European" provenance, is unresolved in EUFORGEN. Timber mostly comes from cultivated trees.
• The Wood Database lists J. regia but not specimen origin; Tropix and Wood Database share shrinkage numbers whose common origin I could not establish. Black walnut data are North American and were kept separate.
• Tropix labels are partly inferred from a garbled PDF; LWF's bending-strength entry looks inconsistent and was not used.
• Drying: sources disagree on speed and collapse/casehardening risk; one informational schedule; steaming data are for black walnut.
• No sawing patterns, log storage times, or current European prices were verified.
• EN 350 class: Tropix gives class 3 (moderately durable) for heartwood; I did not independently read the standard.

Key points

• J. regia timber comes from scattered, cultivated trees; supply is small and burl and butt logs carry the value.
• Density is about 640-680 kg/m3 across three European-focused sources; black walnut (610 kg/m3, Janka 4,490 N) is American and distinct.
• Sapwood is wide (5-10 cm) and non-durable; steaming data are for black walnut only.
• Sources conflict on drying speed and collapse risk; run a trial before using the single Tropix schedule.
• Machines, glues and finishes well, but keep wet boards from iron and check alkaline glues.
• Heartwood is moderately durable (Tropix class 3); not for permanent wet use.