Western Redcedar Characteristics for Epoxy Tables
Western redcedar (Thuja plicata) is a distinctive timber known for its straight grain and uniform, coarse texture. The heartwood ranges from reddish or pinkish brown to dull brown, while the sapwood is nearly white and narrow, often not more than 3 cm (1 in.) wide. When preparing live-edge slabs or boards for an epoxy river table, woodworkers often highlight this tonal contrast along the epoxy interface. Because the wood has a coarse texture, applying an epoxy seal coat prior to the primary resin pour is critical to seal open wood pores and prevent air bubbles from emerging into the curing epoxy.
Mechanical Properties and Stability Data
The mechanical properties and dimensional stability figures documented by the USDA Forest Products Laboratory show how western redcedar performs under load and moisture transitions:
| Property | Green | 12% Moisture Content |
|---|---|---|
| Specific Gravity | 0.31 | 0.32 |
| Modulus of Rupture (lbf/in2) | 5,200 | 7,500 |
| Modulus of Elasticity (million lbf/in2) | 0.94 | 1.11 |
| Compression Parallel to Grain (lbf/in2) | 2,770 | 4,560 |
| Compression Perpendicular to Grain (lbf/in2) | 240 | 460 |
| Shear Strength Parallel to Grain (lbf/in2) | 770 | 990 |
| Side Hardness (lbf) | 260 | 350 |
Shrinkage percentages from green to ovendry condition:
- Radial shrinkage: 2.4%
- Tangential shrinkage: 5.0%
- Volumetric shrinkage: 6.8%
Dimensional Stability and Seasonal Movement
Western redcedar exhibits very low shrinkage compared to many common table woods. Even so, managing dimensional stability is critical when uniting natural timber with rigid epoxy resin. Wood naturally expands and contracts with changes in relative humidity. Slabs must be thoroughly dried to a stable moisture content before casting to minimize internal stresses along the epoxy bond line.
Understanding the relationship between tangential and radial movement is especially relevant for flatsawn slabs. Tangential shrinkage is 5.0%, while radial shrinkage is 2.4%. Because tangential movement is roughly double radial movement, flatsawn boards experience considerably more dimensional change across their width than quartersawn boards. Epoxy resin forms a rigid, inert structure that does not move with humidity. To keep the composite river tabletop intact over time, builders must allow for seasonal movement when mounting the tabletop to its base rather than locking the slab down with rigid fasteners.
Hardness and Structural Performance
Western redcedar is lightweight, with a specific gravity of 0.31 in green condition and 0.32 at 12% moisture content, and it is classified as moderately soft. Its side hardness measures 260 lbf green and reaches 350 lbf at 12% moisture content. By comparison, harder woods resist dents, scratches, and surface wear much more effectively. Because western redcedar is soft, tabletops built from this species can indent under concentrated pressure, requiring protective care or durable topcoats in demanding environments.
From a structural standpoint, western redcedar provides a modulus of rupture of 7,500 lbf/in2 and a modulus of elasticity of 1.11 million lbf/in2 at 12% moisture content. Compression parallel to the grain reaches 4,560 lbf/in2, while compression perpendicular to the grain is 460 lbf/in2. Shear strength parallel to the grain measures 990 lbf/in2. Because the species is low in strength when used as beams and low in shock resistance, wide or heavily loaded epoxy river tables require well-designed subframe support beneath long spans.
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: Western redcedar heartwood is naturally very resistant to decay, but with a low side hardness of 350 lbf at 12% moisture content, builders should take extra care when clamping and surfacing slabs; see the USDA Wood Handbook (FPL-GTR-282) for complete species documentation.