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Solid wood is hygroscopic—it absorbs and releases moisture as the surrounding air changes. That means your furniture subtly expands in humid summers and contracts in dry winters. A few simple habits keep it stable, minimize cracks or warps, and preserve the finish year-round.1

Quick answer: your target indoor conditions

Keep your home between ~30–50% relative humidity (RH) and a steady 60–80 °F (16–27 °C). This range keeps both people and wood happy and helps prevent mold above 60% RH and excessive shrinkage below ~30% RH.7,14
Season Typical Indoor Goal What Wood Is Doing Your Actions
Winter (heating on) 30–40% RH; 60–72 °F (16–22 °C) Air dries → wood contracts across the grain; gaps and minor checks risk increases.1 Run a humidifier with a humidistat; keep furniture away from heat vents/radiators; use coasters and soft pads under hot items; dust with a barely damp cotton cloth.0,7,15
Summer (humid) 40–50% RH; 68–78 °F (20–26 °C) Air moistens → wood swells; joints can feel snug; finishes soften if overheated.1 Use AC or dehumidifier; increase airflow; wipe spills fast; add felt pads to prevent stuck drawers or doors; reduce direct sun/UV with blinds or UV-filter film.16
Any time Stable = good (limit swings) Rapid RH swings stress wood and finishes (checking, warping).1 Monitor RH with a hygrometer; move pieces out of direct sunlight; avoid garages/attics/basements for storage due to large fluctuations.0,2

How wood actually moves (and why it matters)

When protected from liquid water and direct heat, a wood’s moisture content follows the room’s RH and temperature toward an “equilibrium moisture content” (EMC). More RH → higher EMC → slight swelling; less RH → lower EMC → slight shrinkage. Movement is greatest across the grain, minimal along the grain.11,12

Rule of thumb: plain-sawn boards move about twice as much across their width as quarter-sawn boards of the same species—one reason quarter-sawn white oak is popular for stable tops and doors.8

Placement choices you control

  • Keep distance from heat sources. Avoid fireplaces, baseboard heaters, or floor/ wall vents that drive localized dryness and heat; leave clear space rather than parking furniture right over/against a vent.0
  • Limit direct sunlight and UV. Fading and finish breakdown accelerate under UV. Use blinds/curtains or UV-filter film to cut exposure.16
  • Choose stable rooms for storage. Skip attics, basements, or garages—large RH and temperature swings are risky.0

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Finish-specific care (what to use—and avoid)

Oiled finishes (hard-wax oils, Danish oils). Clean with the maker’s neutral pH cleaner; periodically refresh with the compatible maintenance oil if sheen or protection fades. For example, hard-wax oil systems have specific cleaners and refreshers—follow the manufacturer’s schedule.9

Film finishes (lacquer, shellac, polyurethane, conversion varnish). Dust with a soft cotton cloth; spot-clean with mild, diluted detergent and water, then dry immediately. Avoid ammonia or strong solvents unless specified by the maker (they can soften or haze finishes).6

Avoid silicone polishes. Silicone residues can contaminate surfaces and cause “fish-eye” defects if the piece is ever refinished. If you use wax, sparingly apply a high-quality paste wax; frequent rewaxing isn’t recommended.5,6

Tip: Whatever the finish, microfiber or old cotton T-shirts work well for dusting. Mist the cloth (not the furniture) to pick up dust, then buff dry.6

Winter checklist (dry air)

  • Target 30–40% RH using a humidifier with an integrated humidistat. Clean tanks regularly to avoid bacteria buildup.7
  • Relocate pieces at least a safe distance from heaters/vents (dry, hot air accelerates shrinkage and finish stress).0
  • Use coasters/trivets and avoid leaving hot mugs or damp planters directly on tops.
  • Expect small, reversible seasonal gaps (e.g., at panel edges). Don’t force sticky drawers—add a felt pad or wax the runners.

Summer checklist (humid air)

  • Target 40–50% RH using AC or a dehumidifier; ventilate well to prevent musty odors and mold risk above 60% RH.17
  • Reduce direct sunlight on tops and arms (blinds/curtains; rotate decor occasionally).16
  • Wipe spills and condensation rings quickly to prevent swelling at joints and white “blush” in some finishes.

Measuring & monitoring (low-effort, high impact)

Place a simple digital hygrometer in the room to track RH. If you see persistent readings below ~30% in winter or above ~50–60% in summer, adjust with humidification/dehumidification. Keep temperature steady within common comfort ranges (roughly 60–80 °F).7,14

Recommended video: “Is Wood Movement a Myth? Analyzing 30 Years of Data” by Jonathan Katz-Moses. It’s an approachable explanation of how moisture drives movement and how to plan for it seasonally. 18

When to worry (and when not to)

  • Normal: hairline seasonal gaps, doors/drawers slightly tighter/looser as seasons flip.
  • Investigate: rapid cracks, lifted veneer, pronounced top cupping, stuck doors that don’t resolve as RH stabilizes—check for a localized heat source, direct sun, or large RH swings first.0,16

FAQs

1) What RH should I aim for to protect wood furniture?

Generally 30–50% RH works well indoors; avoid long periods above ~60% (mold risk) or below ~30% (shrinkage, checking).7

2) Does sunlight really harm wood?

Yes. UV and visible light fade dyes and finishes and can embrittle coatings over time. Use blinds/curtains or UV filters on glazing.16

3) How far from heat sources should I keep furniture?

Avoid direct proximity to radiators, baseboard heaters, and floor/wall vents; keep comfortable clearance so hot, dry air doesn’t blast the piece. Museums explicitly advise avoiding these locations.0

4) Is waxing good for every finish?

Not always. If you wax, use a quality paste wax sparingly. Avoid silicone-containing polishes—they can cause problems if the piece is ever refinished.5,6

5) My tabletop has tiny gaps in winter—did it fail?

Probably not. Wood shrinks as RH drops; small seasonal gaps are normal and usually close in summer.1

6) Do oiled finishes need different care than lacquer or poly?

Yes. Oiled/hard-wax oil finishes are maintained with maker-approved cleaners and occasional refresh oil; film finishes prefer mild soap-and-water spot cleaning and gentle dusting.9,6

7) What’s “EMC” and why should I care?

Equilibrium Moisture Content is the moisture level wood settles at for a given RH and temperature. EMC shifts seasonally, driving slight dimensional change.11

8) Can I store furniture in my garage or attic?

Best to avoid. These spaces swing widely in RH and temperature, increasing risk of cracking, warping, or finish failure.0

9) How do I monitor RH without overthinking it?

Place an inexpensive digital hygrometer where the furniture lives. If RH sits out of range for days, adjust with humidifier/dehumidifier or HVAC settings.7

10) Will quarter-sawn wood really move less?

Yes—quarter-/rift-sawn stock exhibits less tangential movement than plain-sawn, making it a smart choice for large panels and tops.8

11) Are water rings permanent?

Often not. “Blush” (moisture trapped in some film finishes) may dissipate as the finish dries; stubborn marks may need professional care. Prevent them with coasters and quick wipe-ups.6

Citations

  1. USDA Forest Products Laboratory. Moisture Relations and Physical Properties of Wood, Ch. 4.
  2. Canadian Conservation Institute. “Basic care – Furniture and objects made of wood.”
  3. Canadian Conservation Institute. “Furniture, wooden objects and basketry.”
  4. USDA FPL. Wood Handbook, Ch. 4: Moisture & Physical Properties.
  5. USDA FPL. “Drying and control of moisture content and dimensional changes.”
  6. Workshop Companion. “Wood Movement: Understanding Moisture, Shape, and Movement.”
  7. US EPA. “Indoor Relative Humidity (Mold Course),” keep RH below 60%, ideally 30–50%.
  8. National Wood Flooring Association. “Problem Prevention”—recommendations for 60–80 °F and 30–50% RH.
  9. Canadian Conservation Institute. “Care of Furniture Finishes.”
  10. US National Park Service. “Silicone in Furniture Waxes and Polishes.”
  11. Canadian Conservation Institute. “Agent of Deterioration: Light, UV & IR.”
  12. US EPA. “A Brief Guide to Mold, Moisture, and Your Home.”
  13. Rubio Monocoat. “How to care for your Rubio Monocoat finished furniture.”
  14. YouTube: Jonathan Katz-Moses — “Is Wood Movement a Myth? Analyzing 30 Years of Data.”
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