Practical Guide to Drying and Storing Tonal Wood

If you work with wood to build musical instruments — or you're just getting started in lutherie — there's one factor that makes the difference between a piece of wood that resonates and one that cracks: how you dry it and how you store it.

You don't need an industrial warehouse or thousands of euros worth of equipment. With the right knowledge and a few simple tools, you can keep your tonewoods in optimal condition even in a small workshop or at home.

This guide gets straight to the point. No unnecessary theory. Just what you need to know so that every piece of spruce, cedar, rosewood or maple reaches your workbench ready to sing.

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Moisture and wood: what you need to know

Wood is a living material. Even after it's been cut and dried, it continues to absorb and release moisture depending on its surroundings. Think of it as a slow sponge: if the air is humid, it takes in water; if it's dry, it lets it go. This causes swelling, shrinkage, warping or cracking.

Three key concepts (and nothing more)

Moisture Content (MC) — This is the percentage of water in the wood relative to its dry weight. Freshly cut green wood can have an MC of 40–80%. For lutherie, we need between 6% and 10%, ideally around 7–8%.

Relative Humidity (RH) — This is the percentage of moisture in the air. It's measured with a hygrometer. For a lutherie workshop, the ideal range is between 40% and 55% RH.

Equilibrium Moisture Content (EMC) — This is the point where the wood stops absorbing or releasing moisture because it's in balance with the surrounding air. If you keep your workshop at 45% RH, the wood will stabilise at around 8% MC. That's exactly what we're after.

Reference table: ambient RH → wood MC

Ambient RH	Wood MC	Suitable for lutherie?
20–30%	4–6%	Too dry — risk of cracking
30–40%	6–8%	Acceptable — lower end
40–55%	7–10%	IDEAL for lutherie
55–65%	10–12%	Too humid — risk of warping
65–80%	12–16%	Dangerous — mould, severe warping

Approximate values. Exact figures vary by species and temperature.

Why is this so critical in lutherie?

A spruce soundboard is between 2 and 3 mm thick. At that thinness, any change in humidity causes movement. If the wood isn't stabilised at the right MC before building, the instrument can develop soundboard cracks, neck distortion, bridge lift or unpredictable tonal shifts. Proper drying isn't a luxury — it's the first step in a solid build.

Temperature matters too

Relative humidity and temperature go hand in hand. Warm air can hold more moisture than cold air, so when you heat a room in winter without adding moisture, RH drops. And when summer heat rises without ventilation, RH can spike. The ideal temperature range for a lutherie workshop is 18–24 °C (64–75 °F). Avoid peaks above 30 °C (resins can activate) and below 10 °C (condensation risk).

Acclimatisation: the step many forget

When you receive new wood — regardless of where it comes from — don't work it the same day. Leave it in your workshop, out of the box or packaging, for 1 to 2 weeks to adapt to the RH and temperature of your space. Wood needs time to reach equilibrium with its new environment. If you work it before acclimatisation, it can shift after gluing and ruin the build.

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Essential tools

You don't need much. With these tools you can control the entire process. We've ranked them from most essential to recommended.

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Drying step by step

Depending on where you buy and the type of piece, wood can arrive at different moisture levels. Some pieces come ready to work; others need a drying or stabilisation process before use. There are also situations where you'll need to recondition wood: if you buy green wood from a local sawmill, if you receive pieces after a long container voyage, or if your stock has been stored in an overly humid environment.

Method 1: Air drying (the classic)

This is the simplest method and the one that best preserves the acoustic properties of the wood. It requires no special equipment, but it does take patience.

1. Prepare the area. Find a covered, ventilated space protected from direct sunlight. A garage with ventilation, a shed or a room with a window will do. Avoid unventilated basements and attics where summer heat is extreme.

2. Stack correctly. Place stickers (dry wood strips of 15–20 mm) between each piece. The stickers must be perfectly aligned vertically, one above the other. This allows air to circulate across all faces evenly.

3. Seal the end grain. Before stacking, apply sealer to the cut ends. Wood loses moisture 10–12 times faster through the end grain than through the side faces. Without sealing, drying will be uneven and checks will appear.

4. Add weight on top. Place an evenly distributed weight on the pile (another thick board, bricks...). This counteracts the wood's tendency to warp during drying.

5. Measure and wait. Check the MC every 2–4 weeks with your pin meter. The general rule: 1 year of air drying per 25 mm (1 inch) of thickness. A guitar soundboard (3 mm) dries much faster, but let it stabilise for several weeks regardless.

Correct stacking: solid base, aligned stickers between layers, weight distributed on top.

Method 2: Accelerated drying in a small space

If you don't have outdoor space or you live in a humid climate, you can create a "mini drying chamber" with items you already have at home.

• A cupboard or small room — The smaller the space, the easier it is to control humidity.
• A small fan — Creates gentle circulation. Don't point it directly at the wood; the airflow should be indirect.
• Silica gel or coarse salt — In open containers inside the space, they help absorb excess moisture passively.
• If possible, a dehumidifier — Not essential, but in very humid areas (basements, uninsulated garages) it speeds things up considerably. Set it to 40–45% RH if you use one.
• Stack as for air drying — Stickers, end-grain sealing, weight on top.

Approximate air-drying times

These times are approximate for air drying in favourable conditions (covered, ventilated, 40–55% RH, 18–25 °C). Accelerated drying with a dehumidifier can reduce them by 30–50%.

Piece type	Thickness	Approx. time	Notes
Soundboard (spruce, cedar)	3–4 mm	2–6 weeks	Usually arrives dry. Stabilise it.
Back/sides (rosewood)	3–5 mm	4–8 weeks	Denser = slower. Seal the ends.
Back/sides (maple, mahogany)	3–5 mm	3–6 weeks	Maple stains easily if RH is excessive.
Neck (mahogany, cedar, maple)	25–30 mm	6–12 months	Critical. A poorly dried neck will twist.
Fretboard (ebony, rosewood)	8–10 mm	2–4 months	Very dense woods. Dry slowly.
Bridge/nut (ebony, rosewood)	10–15 mm	2–4 months	Small pieces. Risk of checks if forced.
Violin/viola plate	15–20 mm	4–8 months	Spruce for violin tops needs years of maturation.

Times assume semi-dry wood (MC 15–20%). Green wood (MC 40%+) may need double or more.

Warning signs during drying

Left to right: end checks, cupping, mould, internal collapse (honeycomb).

• End checks: The end grain dries faster than the core. A sign that sealer is missing or the environment is too dry.
• Cupping: The piece curves into a channel shape. One face is drying faster than the other. Check that stickers are properly placed and flip the piece.
• Dark or greenish spots: Mould. Too much humidity and not enough ventilation. Remove the piece, clean it with diluted hydrogen peroxide and improve air circulation.
• Internal checks (honeycomb): The surface dried too fast and internal tension ruptured the fibres. This is irreversible. A sign of overly aggressive drying.

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Storage: keeping your wood safe

Drying the wood properly is only half the job. If you then store it badly, everything you've gained is lost. Here's how to organise your storage space, even if it's small.

Horizontal or vertical?

Horizontal whenever possible. Soundboards, backs and sides should be stored flat, separated by thin stickers (5–10 mm) with evenly distributed weight on top. This keeps the piece flat and prevents warping.

Vertical only for necks and long pieces that don't fit horizontally. In that case, support them at two points minimum (never just one end) and make sure they don't sag under their own weight.

End-grain protection

Even if the wood is already dry, it's still good practice to keep the ends protected. A bit of paraffin wax, end-grain sealer or even thick masking tape reduces rapid moisture exchange through the ends and prevents micro-checks during seasonal changes.

Humidity control in the storage area

Your goal is to keep RH between 40% and 55%, stable. Sudden fluctuations are worse than an RH slightly out of range but constant. Here are some strategies:

• Cross ventilation: If you can open two air-entry points in your storage space, you create natural circulation at no cost. A small household fan is a good supplement when there's no breeze.
• Coarse salt or silica gel: In open containers inside closed shelving or cabinets. They absorb excess humidity passively. Replace the salt when it clumps.
• In winter with heating: Warm air is dry air. If you drop below 35% RH, place water containers near the heat source or use an evaporative humidifier (cheap and quiet).
• In humid summers: Ventilation is your first line of defence. If your area consistently exceeds 70% RH, a dehumidifier with a hygrostat is the most effective solution (set it to 45% and let it work on its own).

Separating species

Some woods contain resins or oils that can migrate to neighbouring pieces. Rosewood, for example, is known for releasing oils that stain light-coloured woods like maple or spruce. Always separate dark, oily woods from light ones. A simple sheet of brown paper between groups does the job.

Stock rotation

If you buy wood regularly, use the FIFO system: first in, first out. Label each piece with the purchase date. The wood that's been in your stock the longest is the most stabilised and the one you should use first.

Monthly storage check

Set aside 15 minutes a month to inspect your wood. This checklist will guide you:

• ☐ Check hygrometer reading (range: 40–55% RH)
• ☐ Visually inspect tops and thin pieces: any new warping?
• ☐ Check end grain: any starting checks? Reapply sealer if needed
• ☐ Check stickers: still aligned? Is the weight still evenly distributed?
• ☐ Look for mould spots, especially in poorly ventilated areas
• ☐ Empty the dehumidifier tank (or check the drain)
• ☐ Confirm dark woods aren't touching light woods
• ☐ Record the date and RH reading in a notebook or app

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10 mistakes that ruin your wood

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Quick reference table by species

Keep this table handy. The ideal MC and movement sensitivity values will help you prioritise which woods need the most attention in your storage. To learn more about each species, visit our complete tonewood guide.

Species	Primary use	Ideal MC	Sensit.	Notes
Sitka Spruce	Soundboard	6–8%	●●●○	Very sensitive to RH. Keep stable.
European Spruce	Soundboard	6–8%	●●●○	Ideal for classical/violin. Fragile.
Western Red Cedar	Soundboard	7–9%	●●○○	More tolerant than spruce. Watch for resins.
Rosewood (Dalbergia)	Back/sides	7–9%	●●○○	Dense. Oils can stain. CITES.
Mahogany (Swietenia)	Back/neck	7–9%	●○○○	Stable. Good behaviour.
African Mahogany (Khaya)	Back/neck	7–9%	●○○○	Similar to Swietenia. More available.
Maple (Acer)	Back/neck	6–8%	●●●○	Stains easily with moisture. Be careful.
Ebony (Diospyros)	Fretboard	7–9%	●●○○	Very dense. Dries slowly. End checks.
Cypress	Back (flamenco)	7–9%	●●○○	Aromatic. Store separately.
Walnut	Back/sides	7–9%	●●○○	Good weight-to-stiffness ratio.
Sapele	Back/neck	7–9%	●○○○	Very stable. Good mahogany alternative.
Ovangkol	Back/sides	7–9%	●○○○	Dense and stable. Easy to store.
Ziricote	Back/sides	7–9%	●●○○	Oils similar to rosewood. Store separately.
Koa	Top/back	7–9%	●●●○	Highly reactive to RH. Store with care.
Cocobolo	Fretboard/bridge	7–9%	●○○○	Aggressive oils. Always store separately. CITES.

Movement sensitivity: ●○○○ = very stable, ●●●● = highly reactive. CITES = regulated species, requires documentation for international trade.

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Is your workshop ready?

Use this list to assess whether your workspace is ready to receive and preserve tonal wood. Tick off each point you've already sorted.

☐ I have a room hygrometer in the storage area

☐ I have a wood MC meter (pin-type or pinless)

☐ I keep a log of RH readings (notebook or app)

☐ My soundboards and backs are stored flat with stickers

☐ End grain is sealed (wax, sealer or tape)

☐ Dark woods are separated from light woods

☐ There's distributed weight on piles of thin stock

☐ RH stays between 40% and 55%

☐ I've assessed whether I need a dehumidifier or humidifier for my area

☐ I do a monthly visual inspection of my wood

☐ I adjust RH control with seasonal changes

☐ My storage area is covered and ventilated

☐ No direct sunlight hits the wood

☐ New wood is acclimatised before being worked

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Well-cared-for wood is the first step towards an instrument that sounds the way it should. You don't need expensive equipment or huge spaces — just attention, consistency and clear thinking.

© 2025 Maderas Barber. This guide is free to share. If you pass it on, we appreciate it.