Robinia pseudoacacia
Black Locust / Robinia
Class 1 durability from a tree that grows in Europe. One of the only EU-native options that survives outdoors untreated, and a credible domestic answer to tropical exotics like teak.
- Dyrket og fældet i Europa.
- Botanisk gruppe. Nåletræ kommer fra nåletræer, løvtræ fra bredbladede træer.
- Den botaniske familie, som træarten tilhører.
Få besked, når den kommerReferencetræart. Ingen planker på lager lige nu.
Passer det til dit projekt?
Velegnet til
- Outdoor benches and garden furniture that need to survive without preservative treatment
- Thresholds, sills, and entry pieces that take weather and wear
- Fence posts and landscape elements designed as visible objects, not buried hardware
- High-wear interior tops, kitchen islands, workshop benches, retail counters
- Tool handles and turned forms where toughness matters
- Steam-bent components, chair backs, hoops, curved frames
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Træets udseende
Sådan ser det ud
Straight grain, coarse open texture, and a heartwood that lands somewhere between olive-yellow and greenish-gold when freshly cut. UV does the work over the next few months, the green calms down and the wood warms into a deep amber. Sapwood is narrow and pale yellow. The contrast between the two reads cleanly on wide slabs.
- Olive-yellow to greenish-gold heartwood when freshly milled
- Warms to a deep amber over weeks of light exposure
- Narrow pale yellow sapwood, cleanly demarcated from the heartwood
- Coarse open pores read clearly under oil finishes
- Straight grain, coarse texture; very durable.
Bearbejdning
Bearbejdning
Honest warning, this is a hard, tough wood and it will blunt edges. Carbide tooling is sensible, and HSS needs frequent sharpening. Sawing, planing, and sanding all sit around average difficulty for the effort, but tool wear is well above average. It glues and screws cleanly once you pre-drill, and it turns nicely. The standout is steam-bending. Robinia is one of the best European species for it, on a par with white oak.
Overfladebehandling
Takes oils and hardwax oils well; the open pores welcome them. The early colour shift is dramatic, so finish a test piece and leave it in daylight for a fortnight before committing, what you see on the bench is not what the client will see in a month. UV-blocking finishes slow the amber drift if a greener tone is wanted. Sanding to 180 is usually enough; finer grits can burnish the surface and fight oil uptake.
Tørring
Dries slowly and benefits from patience. Surprisingly stable for its hardness once acclimatised, radial movement around 4–5% and tangential 6.5–8% are modest for a 770 kg/m³ wood. Stack with care, weight the top, and expect some end-checking if rushed. Kiln schedules should be conservative.
Hvor meget bevæger det sig?
Træ udvider og trækker sig sammen på tværs af bredden, når luften bliver fugtigere og tørrere. Beregn den forventede sæsonbevægelse i en bordplade af Black Locust / Robinia, før du udformer beslagene.
Forventet sæsonbevægelse
ca. 8,3 mm
Fastgør bordpladen med sargklodser eller beslag med langhuller, ikke med lim eller stramme skruer.
Lineær svindmodel: bredde × (svind ÷ 28 % fibermætning) × sæsonudsving i fugtighed. Bruger 7,25 % tangentialt svind for Black Locust / Robinia. Et planlægningsskøn, ikke en garanti.
Hvad det koster
Sikkerhed og indkøb
- Dyrket og fældet i Europa.
- Status på IUCNs rødliste: den globale bevaringsvurdering for denne træart.
Not recommended for direct food contact. The bark, leaves, and seeds carry toxic compounds, and while the heartwood is considered the safer part of the tree, we would not specify it for cutting boards or utensils. The dust is a known irritant and sensitiser, some woodworkers report nausea from prolonged exposure. Run dust extraction and a fitted respirator, not just a paper mask.
Læs hele guidenDybdegående noter om tegning, farveændring, bearbejdning og stabilitet.
What Robinia actually is#
Robinia pseudoacacia, black locust, is the strongest and most durable timber in this catalogue, and it grows across Europe like a weed.
The numbers are not close. At 7,560 N Janka it is the hardest measured species here. Its modulus of rupture of 130 MPa and elastic modulus of 14.0 GPa are the highest measured figures in the catalogue. And it is rated decay class 1, very durable, matched only by yew.
That combination, tropical grade durability from a fast growing European species, is unusual enough to be worth stating plainly: robinia does what teak and ipe do, without a tropical supply chain.
Why it is not more widely used#
Three reasons, none of them about performance.
It is hard to convert. At this density and hardness it blunts tooling fast and asks a great deal of machines, and small sawmills often decline it.
It grows badly for timber. Robinia is prone to twisting, forking and spiral grain, so long straight clean lengths are scarce even where the tree is abundant. Most of what is cut ends up as fence posts and stakes, applications where its durability is used and its form does not matter.
It has an image problem. In much of Europe it is regarded as an invasive nuisance rather than a timber species, which keeps demand and therefore processing infrastructure low.
Spørgsmål fra købere
Det spørger købere om
Is Robinia really as durable as tropical hardwood?
Yes, and that is its main argument. It is rated decay class 1, very durable, the highest rating in this catalogue alongside yew, and it performs comparably to teak or ipe in ground contact. Because it grows fast across Europe it offers tropical grade durability without a tropical supply chain, which is a rare combination under EUDR.
How hard is it?
At 7,560 N Janka it is the hardest measured wood in this catalogue, above hornbeam at 7,260 N and half again as hard as European oak. Its modulus of rupture of 130 MPa and stiffness of 14.0 GPa are also the highest measured figures here. It is a genuinely formidable timber.
Is it toxic?
The bark, leaves and seeds are toxic, containing robin and robinin, and the wood is recorded here as not food safe. Dust is irritant. Do not use it for chopping boards, food contact surfaces or anything a child might chew, and run extraction when machining.
Why is it treated as invasive in some countries?
Robinia is native to North America and was introduced to Europe in the seventeenth century. It spreads readily by root suckers and fixes nitrogen, altering soil chemistry, and several European countries list it as invasive. That is an ecological concern about planting rather than a restriction on timber, and harvesting established stands is generally viewed favourably.
Mekaniske egenskaber
Tekniske data
Offentliggjorte referenceværdier. Når kilderne er uenige, vises intervallet, og den typiske værdi bruges til skalaerne ovenfor.
| Massefylde (kg/m³)Masse pr. kubikmeter ved ca. 12 % fugtighed. Tungere træ er normalt hårdere og stærkere. | 700–830 kg/m³typisk 770 kg/m³ |
|---|---|
| Janka-hårdhed (N)Den kraft, der skal til for at presse en stålkugle halvt ind i træet. Standardmålet for modstand mod trykmærker. | 7,000–8,200 Ntypisk 7.560 N |
| MOR: brudmodul (MPa)Bøjningsstyrke: den belastning, hvor en bjælke brækker. | 130–150 MPa |
| MOE: elasticitetsmodul (GPa)Bøjningsstivhed: hvor meget en hylde eller bordplade bøjer ned under belastning. | 14.0–16.0 GPa |
| Radialt svindSvind på tværs af årringene fra frisk til ovntørt træ. Kvartskårne brædder bevæger sig på denne måde. | 4.0–5.0 % |
| Tangentialt svindSvind langs årringene. Plansavede brædder og de fleste planker bevæger sig på denne måde. |
