Irul (Pyinkado) Wood (Xylia xylocarpa): Properties, Density & Uses

What Irul (Pyinkado) is

Irul is a dense, extremely durable hardwood from the pea and legume family (Fabaceae), native to India and mainland Southeast Asia. Its accepted botanical name is Xylia xylocarpa, and a great deal of older railway and engineering literature calls it Xylia dolabriformis — the same wood under a superseded name.1 The genus name comes from the Greek xylon, “wood,” which suits a timber genuinely hard enough to earn the trade label “ironwood.”

The many names it travels under cause real confusion, so it is worth being clear. In Kerala and Tamil Nadu it is Irul (also Irumullu, Kadamaram); across the Deccan and much of the north it is Jamba or Jambu; in Myanmar it is Pyinkado; and international traders know it as Burma Ironwood.6 These are all one species. Indian forestry work settled the point long ago — Irul and Pyinkado were confirmed to be the same tree.4 If you are handed an old specification that names “Xylia dolabriformis” or “Jamba,” you are looking at Irul.

Where it grows

Irul is native across South and Southeast Asia. In India it occurs in the Western Ghats — Kerala, Karnataka, Maharashtra and Tamil Nadu — and through central and eastern India in Odisha, Andhra Pradesh, Telangana and Madhya Pradesh; beyond India it grows in Myanmar, Thailand, Laos, Cambodia and Vietnam, and has been introduced into East Africa.13 It favours dry evergreen, mixed deciduous and dry dipterocarp forest up to about 850 metres. The tree is deciduous, reaching 20–40 metres with a straight cylindrical bole often clear for 12 metres or more, 40–60 cm in diameter, with occasional small buttresses — a form that yields long, sound structural lengths.3

On the supply side, buyers should understand where the wood actually comes from. Irul is planted within its natural range, including in forest-department plantations and in the afforestation of degraded land, so both wild and cultivated stands exist.3 In practice, though, most Irul on the market is forest-sourced sawn timber, and because the natural distribution is limited and demand has been heavy, foresters increasingly recommend expanding plantations and selecting better planting stock.2 In Kerala specifically it is a native Western Ghats tree — a host plant for many butterflies — rather than a large commercial monoculture.4

Weight, density and hardness

Weight is Irul's defining property: it is one of the heaviest structural timbers you will meet in the Indian trade. The published figures span a range, and they are worth quoting honestly rather than picking one number. PROSEA gives an air-dry density of 880–1170 kg/m³ (occasionally to 1330) at 15% moisture; ITTO reports about 1140 kg/m³ air-dry at 12% moisture; and the US Forest Products Laboratory records 833–1121 kg/m³.23 For working purposes, mature forest-grown Irul air-dries to roughly 950–1120 kg/m³ (commonly quoted around 1000 kg/m³), while young plantation-grown material is appreciably lighter at nearer 800–850 kg/m³. That is broadly double the weight of a light plywood face species such as okoume.

The hardness follows from the density and is well corroborated. FPL puts Janka side hardness at about 2,220–2,275 lbf dry, and ITTO independently reports roughly 999 kgf (about 2,200 lbf) — two sources arriving at much the same place, so the ~2,200 lbf figure is solid.3 In bending it is very strong: modulus of rupture around 135–142 N/mm² and stiffness (modulus of elasticity) between about 12.9 GPa for plantation stock and 16.6 GPa for mature natural timber, with compression parallel to the grain of roughly 68–80 N/mm².3 That bending strength is exactly what made Irul a premier railway-sleeper and bridge timber for generations.

Working and seasoning

None of this comes for free, and Irul is a demanding wood to work. Sawing is difficult and the timber blunts tools quickly once dry, though it is noticeably easier to cut while still green.3 For machining and planing the blunting effect is severe, so ITTO recommends tungsten-carbide-tipped cutters and a reduced cutting angle; with those in hand a good, smooth finish is achievable.3 The single most important point for anyone assembling crates or skids is fastening: the wood is so dense that it must be pre-bored before nailing or screwing, or it will split.3 Plan on pilot holes, or move to bolted connections, for any heavy load-bearing member.

Seasoning is the other place to slow down. Irul dries slowly and is prone to surface checking, splitting and warping if it is pushed too fast; careful, slow drying is essential, and a mild kiln schedule exists for it.2 Total shrinkage is moderate but not negligible — about 6.7% tangential and 3.3% radial from green to oven-dry, a tangential-to-radial ratio of roughly 2.0, which carries some tendency to distort.3 The practical lesson for packing use is simple: buy well-seasoned stock. Freshly sawn Irul is easier to cut, but if it is dried badly the skids will check.

Durability and treatability

This is where Irul truly earns its reputation. Its natural durability is rated very high — ITTO durability class 1, the top of the scale — with strong resistance to decay fungi, insects, termites and even marine borers.3 The field record backs the rating: untreated sleepers have lasted around 12 years in Thailand and 20–24 years in India, service life varying with climate and exposure.24 The one caveat is the narrow sapwood (up to about 2.5 cm), which is vulnerable to powder-post (Lyctus) beetle; the heartwood is the durable part.2

Treatability runs the opposite way to durability, as it usually does with dense heartwoods. The sapwood takes preservative readily, but the heartwood is very resistant to penetration and is effectively untreatable.3 In practice this rarely matters, because the heartwood's own durability means preservative treatment is normally unnecessary for the uses Irul is put to.

Sustainability and sourcing

On conservation status, Irul is currently assessed as Least Concern on the IUCN Red List (2019) — it does not meet a threatened category at the global level.5 It is not CITES-listed, and in India it is not scheduled under the Wildlife Protection Act, though normal forest-harvest regulations apply. Because most commercial Irul is forest-sourced sawn timber from natural stands and plantation supply is still limited, foresters recommend expanding plantations to relieve pressure on wild populations.23 A buyer who wants a clean sustainability story should ask the supplier for legal, documented sourcing — forest-department origin with the relevant transit-pass paperwork.

What Irul is used for

Irul is a classic heavy-construction and engineering timber. Its long service list runs to railway sleepers and crossties, bridge work, piles, girders, decking, marine piling, wagon and wagon-floor boards and mine props; in building it goes into posts, beams, rafters, fence posts and hard-wearing flooring, and it has long stood in as a substitute for Sal and Teak in beams and house frames.13 It also finds use in agricultural implements, cart-making, tool handles, turnery and boat-building, and lower grades go to fuelwood, charcoal and wrapping-paper pulp.4

For the packing and materials-handling trade, the point to hold onto is that Irul is a solid-timber member, not a panel material. Its density, strength and durability make it a natural choice for the heavy-duty load-bearing parts of a crate — skids, bearers, gluts, runners and frames under machinery cases and heavy engineering export packing — where it complements plywood or boarded case panels rather than replacing them. It is emphatically not a peeler species: the extreme density and interlocked grain make rotary peeling into veneer uneconomic, so you will not see Irul plywood.23 (One naming trap worth flagging: the lighter African timber Afzelia xylocarpa is a different species entirely — do not confuse the two.)

How Cochin Wood uses Irul (Pyinkado)

We should be plain about our position. Cochin Wood is a Kerala plywood and timber manufacturer, part of a group that has operated in Perumbavoor since 1986. Irul reaches us as sawn timber, not as a panel or veneer — there is no such thing as an Irul plywood, and we would not claim one. Where a heavy machinery crate or an export case needs dense load-bearing runners, bearers and skids beneath a plywood or boarded case, a hardwood like Irul sits in exactly the right use-class — the same slot we normally fill with our jackwood and rubberwood runners. The case panels themselves we build from plywood, whether that goes into plywood boxes and crates, pallets or block boards and flush doors. If you are weighing timber options, our full range is on the products page.

One compliance note for exporters, whatever the timber: any solid-wood packaging — Irul skids included — still needs ISPM-15 heat treatment or fumigation with the IPPC stamp before it ships, regardless of the wood's natural durability. Tell us the thickness, size, monthly quantity and delivery location and we will qualify the requirement and quote against it.