Thermally Modified Korina 5/4x6 Grooved Deck Board

Korina is the lumber trade's name for Terminalia superba, a West African hardwood most people have seen without knowing it — Gibson built the Flying V and the Explorer out of it in the late 1950s and the name stuck. Elsewhere in the timber world the same tree is sold as Frake, Afara or Limba. It has always been a pleasant wood to work: straight-grained, pale, light for a hardwood, and predictable under a blade. It has also, historically, been useless outdoors. Untreated Korina has almost no natural resistance to decay, and a board left exposed to weather will not see out many seasons. Thermal modification changes that completely. The lumber is cooked in a sealed kiln at roughly 400°F in an oxygen-starved atmosphere — no preservatives, no copper, nothing added but heat and steam. The heat breaks down the hemicellulose that decay fungi feed on and permanently reduces the wood's ability to take on moisture. What comes out is a genuinely different material: rot-resistant, dimensionally stable, and a deep even brown all the way through the board rather than a colour sitting on the surface. The numbers tell the story better than any sales pitch. Untreated, this species moves about 4.3% radially and 6.3% tangentially through a change in humidity. After modification both fall below 2%. That is the difference between a deck that cups, gaps and pulls its fasteners through a wet spring and one that simply stays flat. The trade-off is strength: the process costs roughly a quarter of the wood's breaking strength, which is why modified Korina belongs in decking, cladding, ceilings, trim and pergolas — and not in a structural span. Design the framing in something else and let the Korina be the surface you actually see. Left alone it weathers to the soft silver-grey that every exterior wood eventually reaches. If you want to keep the brown, an oil finish carries the colour and is easy to refresh a few years later without stripping anything back. We carry it as 5/4×6 decking in two profiles — grooved for hidden fasteners, or square-edged if you would rather face-screw and plug.

Color

A deep, even golden to chocolate brown carried right through the board by the heat treatment rather than sitting on the surface as a stain. Sometimes shows grey to nearly black streaking. Weathers to a soft silver-grey if left unfinished.

Grain

Straight to slightly interlocked.

Texture

Uniformly coarse, with a moderate natural luster.

Durability

Highly resistant to rot and decay once thermally modified — and because the process removes what fungi feed on rather than adding a preservative, that resistance runs through the whole board and cannot wear off, leach out or need re-applying at a cut end. Untreated Korina is the opposite: not durable, and not a wood to put outdoors.

Working

Machines, sands and finishes cleanly much like the unmodified wood. Thermally modified timber is more brittle than raw stock, so pre-drill near board ends and at fasteners, keep carbide tooling sharp, and expect a fine dark dust worth collecting. Takes both oil and water-based stains and paints well.

Drying

Comes out of the modification kiln at a very low moisture content and largely stays there — treated wood takes on far less moisture than untreated stock and moves very little in service. No further seasoning needed before installation.

Common uses

Decking, Siding, Cladding, Ceiling, Trim, Beams, Pergolas

Origin

West & Central Africa

Botanical family

Terminalia superba (Combretaceae)

Also known as

Frake, Limba, Black Limba, Afara, Terminalia superba

Specifications

Material

Thermally Modified Korina

Brand

Ghent Wood Products

SKU

TMK-54X6-GRV

Usage

Decking

Pattern

S4S Grooved

Nominal size

1-1/4 × 6

Net size (actual)

1" × 5-1/2"

Coverage per LF

5-1/2"

Condition

Kiln-dried (KD)

Sold by

LF

Weight

1.37 lb

Availability

Made to order