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Black Beech

Black beech was used in house construction for framing, flooring, subflooring and panelling, and also in framing and constructional use in fence posts, gates, rails, bridges and piles.

The limited quantities now available are largely employed in uses where the timber’s stability, machining properties and appearance are paramount, such as for tool handles, furniture, exposed floors, panelling and bench tops.

Description

blackbeech_90Black beech heartwood timber is reddish- brown when freshly cross-cut, with a mid-dark brown surface face on sawing, often with blackish streaks.

After drying, the timber lightens to a straw colour, with darker blackish streaks (possibly pathological).

The sapwood is whitish yellow when freshly sawn, seasoning to a whitish brown or amber.

Black beech typically grows to altitudes of 700m throughout the foothills of the North Island axial ranges and the Taranaki- Wanganui area.

It is also common in the north-west of the South Island, though forms which are botanically intermediate between black and mountain beech occur on the eastern side of the South Island as far south as Foveaux Strait.

It grows up to 30m in height with a diameter at breast height of up to 1m. Black beech is so named for the sooty mould that occurs in the honeydew on the outer bark.

The bark of older trees is deeply furrowed, rough and dark to almost black in older trees.

Botanical name: Nothofagus solandri

Other common names: Tawhairauriki

Strength: Like all native beech species, the timber has excellent strength and stability properties.

Durability: Durability is variable. Neither the sapwood nor the heartwood are subject to rot except in high hazard conditions. True heartwood can survive for long periods in the ground provided it does not contain pathological heartwood or sapwood.

Finishes: Not applicable.

Working properties: Tension in the wood can lead to dulling of saws and machine knives, and like other high density timbers there may be problems with seasoning.

Appearance: Black beech heartwood timber is reddish- brown when freshly cross-cut, with a mid-dark brown surface face on sawing, often with blackish streaks.

Properties

Like all native beech species, the timber has excellent strength and stability properties.

It has a fine even texture, good machining, bending and finishing properties and takes stains well The air-dry density ranges from 650 – 720 kg/m³, with a modulus of rupture of 100 MPa and a modulus of elasticity of 13.7MPa. The compression strength parallel to the grain is higher than other beech species, at 55 MPa.

Black beech has properties which are very similar to Mountain beech, except in durability, where black beech is less durable, 50x50mm posts lasting 10-15 years in the ground.

Tension in the wood can lead to dulling of saws and machine knives, and like other high density timbers there may be problems with seasoning.

Shrinkage of the heartwood can be high, up to 6% from green to 12% moisture content in the tangential direction, and 4% radially.

Durability is variable. Neither the sapwood nor the heartwood are subject to rot except in high hazard conditions. True heartwood can survive for long periods in the ground provided it does not contain pathological heartwood or sapwood.

The heartwood timber is, however, classed as moderately durable (lasting 10-15 years in ground), which gives an equivalent Hazard class of H3.1.

Availability
Limited supplies of Blackbeech are available. Refer to the New Zealand Farm Forestry Association website for information regarding local timber suppliers.