Harmattan cracks wood: saving the guitar, the parquet and the door that suddenly closes

Wood is a sponge with a grain, and harmattan runs the sponge on a cycle: dry air pulls moisture from the cells, the fibres shrink, and everything held together by fibre tension tells you about it - the guitar that will not stay in tune, the soundboard seam that opens a hair, the parquet's winter gaps, the door that closes by itself in September and sticks in March. You cannot stop the season; you can negotiate its terms.

The number that matters

Instruments and furniture live happily in the band around 40-55 percent relative humidity; harmattan pushes indoor air into the teens, and the damage is not a single night - it is the duration in the low band, measured in weeks. The honest way to run the season is to know the number: a small hygrometer costs less than a string set and tells you whether anything below is working. That single instrument is the entire first recommendation, and the desk has watched people buy humidifiers and never check whether they achieved anything - the hygrometer is how you know you did.

The cheap interventions that work

• A sealed room, a water surface: a wide pot of water in the corner of the room you keep shut is a humidifier with no marketing; a damp towel over a chair back doubles it. The effect on a closed bedroom is real and measurable by the hygrometer within the hour - and it is a conversation with the season, not a fix, so aim the effort at the room that matters, not the whole house.
• The instrument's case is the safe: keep the guitar, the mandolin, the woodwind in its case, and a case humidifier (the sponge pill or the membrane pad sold for exactly this job) inside the case. The case's tight little box is where a small humidity source actually wins; the open stand in a harmattan room is where the crack starts.
• Loosen the string, or the neck's argument: an acoustic stored through the season at concert pitch under dry tension is asking the top to cup - the store-it-a-half-step-down advice from every luthier is cheap insurance, and if the action suddenly rises before you've played a note, the soundboard is telling you about its moisture, not its tuning.
• Furniture and floors: the polish-and-oil routine before the peak feeds the finish the season will drink; parquet gaps that appear are seasonal - do not chase them with carpentry mid-dry, the wood re-swells and closes in the rains, and a gap filled in January is a floor crowned in June. Door hinges that suddenly bite: a longer screw in the strike plate's top hole, or the planing this desk's fix-it pages already argue for after the year turns.

What the season's other damage list is

The same dryness that splits a bridge tab cracks a plaster wall's hairline and shrinks a wooden doorframe's grip on its paint film; the dust from one is the fuel for the other, which is why the harmattan fire-safety page on this desk tells you to wipe the blades of every fan that runs, and why the electronics article tells you to open nothing without a plan for grit. Wood, paper, cloth and skin all take the same season; the number on the hygrometer is the household's one shared dashboard, and the house that watches it saves itself a string set, a luthier's opinion, and a door's dignity, every single year.