Storing Wood Slabs and Finish Lumber for Epoxy Builds

Why Wood Storage Matters Before an Epoxy Pour

When preparing kiln-dried wood slabs or lumber for an epoxy river table or solid tabletop, maintaining dimensional stability is critical. Wood continues to exchange moisture with the surrounding atmosphere even after drying. According to the USDA Forest Products Laboratory in the Wood Handbook (General Technical Report FPL-GTR-282), kiln-dried items intended for furniture, cabinet work, interior trim, and remanufacture must be stored under controlled relative humidity conditions to prevent unwanted moisture regain and dimensional changes.

If wood absorbs moisture unevenly prior to straight-line ripping, jointing, or edge gluing, subsequent shrinkage can lead to open joints and splitting at the ends of panels. When embedding lumber in epoxy resin, keeping moisture stable prior to fabrication prevents internal stresses and movement. Always follow the resin maker’s data sheet regarding shop environment and surface prep, while implementing proper timber storage methods.

Moisture Uptake in Yards vs. Closed Sheds

The type of shelter used for stored lumber dramatically influences how fast wood absorbs atmospheric moisture. Standard 19-mm (nominal 1-in.) hardwood lumber that has been kiln dried to 8% or less and piled solid under a roof in a yard during warm, humid weather can see its average pile moisture content increase at a rate of about 2% per month during the first 45 days. Following that initial period, a moisture uptake rate of about 1% per month can be sustained throughout a humid season.

Moving lumber into an open, roofed shed reduces that initial surge to about 1% per month. Over the course of a year in an open shed in a western location, research cited in the Wood Handbook showed that stock increased in moisture content by 2.7% on the inside of solid piles and 3.5% on the outside of piles.

By comparison, a closed shed provides vastly superior protection. In closed sheds, the moisture uptake rate drops to approximately 0.3% per month. For materials intended for fine woodworking and epoxy fabrication, an enclosed storage area minimizes these dramatic moisture swings.

Foundation Supports and Ground Clearance

Storing lumber correctly inside a storage facility requires adequate elevation off the floor. Moisture can migrate from the ground or concrete surfaces directly into stacked lumber.

• Paved floors: Place material on supports raised at least 150 mm (6 in.) above the floor.
• Unpaved floors: Raise the supports to at least 300 mm (12 in.) above the ground.

In addition, all manufactured and dry stock must be protected from precipitation and spray. When liquid water reaches a solid pile, it tends to be absorbed directly by the wood instead of evaporating, causing localized swelling and uneven moisture distribution.

Controlling Storage Humidity with Temperature Increases

For interior wood products, furniture components, and slabs awaiting tabletop fabrication, simple shelter in an unheated building may not maintain low enough relative humidity. The simplest method to reduce relative humidity in a closed storage area of any size is to heat the space to a temperature slightly higher than that of the outside air.

As documented in Table 13–4 of the Wood Handbook, when there is no source of moisture other than the outside air, wood equilibrium moisture content can be controlled by maintaining a specific temperature differential between the storage space and the outdoor air. Heating air expands its capacity to hold water vapor, thereby lowering the indoor relative humidity. In small, well-enclosed spaces, dehumidifiers can also be used as needed to control moisture, with average storage temperature monitored and relative humidity set to achieve the target wood equilibrium moisture content.

Preventing Over-Drying and Winter End Checking

While excess humidity causes swelling, winter heating can introduce the opposite problem: severe over-drying. Wood in a workshop or factory awaiting fabrication can become excessively dry if the facility is heated to 21 °C (70 °F) or greater when outside temperatures are low, a frequent issue during winter in the northern United States.

Under these cold-weather conditions, outdoor absolute humidity is low, and heating indoor spaces drives the relative humidity down to very low levels. The exposed ends and surfaces of boards dry rapidly toward this low equilibrium moisture content, leading to warping and shrinkage. Specifically, if the equilibrium moisture content drops to 4% or more below the core moisture content of freshly crosscut boards, end checking can develop.

To avoid damaging stock during cold winter months, several simple shop remedies can be used:

• Cover piles of partially manufactured components and slabs with plastic film to retard moisture loss.
• Lower the shop temperature during non-work hours to reduce heating-driven drying.
• Use humidification systems in critical storage and assembly areas to maintain proper equilibrium moisture content.

Stickered vs. Solid Piling Before Table Assembly

When stock is received, measure its moisture content immediately. If stock has picked up moisture or is not within the desired range, stickered storage in an appropriate, conditioned environment can gradually bring the wood to equilibrium. If a large degree of moisture change is needed, the material must be redried before fabrication.

Solid piling (without stickers) should be reserved for material that is already at the target moisture level in an enclosed, humidity-controlled room. By managing temperature differentials, maintaining floor clearance, and protecting board ends from rapid drying, you ensure that slabs remain flat, stable, and ready for precision cutting and epoxy casting.

Sources

• USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282, 2021)

Published October 29, 2026. Sources are linked in the text.

Header image: original graphic by BigEpoxy.com.