Introduction to Karri Wood
Karri (Eucalyptus diversicolor) is a very large hardwood native to southwestern Australia. Woodworkers seeking lumber for long epoxy river tables or wide executive conference desks often appreciate karri because it is commercially available in large dimensions and long lengths free of defects. While resembling jarrah in structure, karri is heavier and prized for applications requiring high flexural strength. Transforming these massive hardwood slabs into epoxy tables requires understanding how its density and movement behave against rigid epoxy resin.
Physical Properties and Shrinkage Figures
To safely embed timber within epoxy, makers must track wood movement values from green to ovendry conditions. The following figures detail the physical properties of karri as recorded by wood science researchers:
| Property | Value |
|---|---|
| Radial Shrinkage (green to ovendry) | 7.8% |
| Tangential Shrinkage (green to ovendry) | 12.4% |
| Volumetric Shrinkage (green to ovendry) | 20.2% |
| Average Density at 12% Moisture Content | 913 kg m–3 (57 lb ft–3) |
Tangential vs. Radial Movement in Table Design
Wood naturally expands and contracts across its grain as relative humidity shifts throughout the seasons. In karri, tangential shrinkage is markedly higher than radial shrinkage, at 12.4% compared to 7.8%. In flatsawn slabs, the wider faces undergo movement primarily across the tangential dimension. Because cured epoxy resin remains dimensionally stable and does not shrink or swell with atmospheric moisture, differential movement can place intense shear stress on the resin-to-wood bondline.
To avoid joint separation, cupping, or splitting, builders must take specific precautions:
- Ensure karri slabs are thoroughly dried to a stable equilibrium moisture content before flattening and pouring.
- Apply a dedicated epoxy seal coat over all live edges and surfaces to slow moisture exchange and block escaping air bubbles.
- Design tabletop mounting hardware with slotted holes or figure-eight fasteners to allow the hardwood to expand and contract across its width without cracking against the resin river.
Density and Machining Considerations
Karri is a heavy hardwood, weighing approximately 913 kg m–3 (57 lb ft–3) at 12% moisture content. High density provides exceptional surface hardness, which helps finished furniture tops resist daily dents and scratches. However, this density also means karri is fairly hard to machine and difficult to work with hand tools. Woodworkers should expect a dulling effect on cutting knives and router bits when flattening slabs or shaping profiles. Carbide tooling and slow, steady feed rates yield the cleanest edge preparation prior to casting.
Sources
USDA Wood Handbook (FPL-GTR-282)
Published October 28, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: The reference material notes that karri is extremely difficult to treat with preservatives, which underlines its dense, impermeable cellular structure; ensure deep mechanical sanding on live edges before casting resin, as detailed in the USDA Wood Handbook (FPL-GTR-282).