A new humidor is an attractive object, and the temptation on the day it arrives is to fill it. That impulse is understandable and it is the single most common reason a first collection goes wrong. The box that has just been unpacked is dry — drier, almost certainly, than anything you intend to keep in it — and the first thing it will do with a row of cigars is take their moisture for itself. Seasoning is the process of satisfying the wood before the tobacco is asked to share a space with it.
Why the wood arrives dry
A humidor is lined with Spanish cedar, chosen because it absorbs and releases moisture readily and because its natural oils and scent suit tobacco. That responsiveness is the whole point of the material, and it is also why the box needs preparing. Between the workshop and your table, the humidor has spent weeks or months in warehouses, shipping containers and delivery vans, none of which are humid. The cedar has given up its moisture to that dry air and arrives at something close to the ambient humidity of a heated building, which in a Canadian winter may be 30 per cent or lower.
Wood in that state is hygroscopic in the most literal sense. Place it in a closed space alongside anything holding more moisture than it does, and it will draw that moisture out until the two reach equilibrium. If the only source in the box is your cigars, the cigars are the reservoir. They dry out, their wrappers tighten and crack, and the hygrometer reports a number that never seems to climb however many packs you add. Nothing is wrong with the packs. The cedar is drinking everything they produce.
What seasoning is
Seasoning means raising the moisture content of the cedar lining until it is in balance with the humidity you intend to hold, so that once the cigars arrive the wood is neither taking from them nor giving to them. It is a one-time process for a new box, and occasionally a repeat process for a box that has been left empty and dry for a long period.
The idea is simple. The execution has two requirements: the moisture has to be delivered slowly, and it has to be delivered as vapour rather than as liquid. Both requirements rule out the traditional methods.
The trouble with the wet sponge
Older advice, still widely repeated, is to wipe the cedar interior with a damp cloth or sponge, or to leave a dish of water inside for a day or two. The intention is sound and the method is not.
Free water on the surface of cedar does not soak in evenly. It swells the outermost fibres immediately while the wood beneath remains dry, and the differential stress that follows is what lifts veneers, opens seams and, in the worst cases, warps a panel so that the lid no longer closes true. A humidor whose lid has lost its seal is a humidor that will never hold a stable reading, and no quantity of packs can correct a gap in the wood.
There is a second problem. Wet cedar is a surface on which mould establishes readily, and a box wiped down and closed is a warm, dark, saturated environment for the several days it takes to dry. Spots of white or grey growth on the interior of a new humidor, appearing within the first fortnight, are almost always traceable to this step.
Distilled water reduces staining but addresses neither risk. The problem is liquid contact, not purity.
Seasoning with a pack
Boveda makes a pack specifically for this purpose, rated at 84 per cent relative humidity, and it resolves both difficulties at once. Inside is the same saturated salt solution as every other Boveda pack, behind the same vapour-permeable membrane. It releases water as vapour only, at a rate limited by how far the surrounding air is from 84 per cent, and it stops when the air reaches that level. The wood absorbs from humid air gradually and throughout its thickness, rather than from a wet surface all at once.
The elevated rating is deliberate. Cedar takes up moisture slowly, and a pack rated at the eventual storage level of 65 or 69 per cent would work, but it would take a great deal longer and would exhaust itself in the process. The 84 per cent pack drives the wood towards equilibrium more quickly without ever presenting it with liquid water. It cannot over-humidify past its rating, so there is no point at which it becomes dangerous to leave it in place.
The process itself asks very little.
- Remove any cellophane, paper or packaging from the interior, and leave the trays and dividers in place so that they season alongside the box.
- Place the seasoning pack inside on a tray or on the floor of the humidor. For a larger desktop humidor, use two. Do not open the pack or pierce the membrane.
- Close the lid and leave the box undisturbed. Opening it to check every few hours only lets the humid air out and resets the process.
- After roughly two weeks, check the pack. If it has stiffened, the cedar has absorbed a large quantity of water and the process is well advanced.
- Remove the seasoning pack, place a calibrated hygrometer inside along with your storage-level packs, and give the box a day or two to settle before reading it.
Fourteen days is a reasonable expectation for a typical desktop humidor. A thick-walled box or a small cabinet may want longer. There is no harm in leaving the pack in place until it goes rigid.
Knowing when it is finished
The most reliable sign is the behaviour of the box once the seasoning pack has been removed and the storage packs are in. If the hygrometer climbs to the rated level of those packs and stays there, the cedar is in balance and no longer drawing from the air. If the reading rises and then sags over a day or two, the wood is still absorbing, and the seasoning pack should go back in for another week.
The state of the seasoning pack itself is a second indicator. A pack that has gone stiff has given up its water to the wood. A pack that remains soft after two weeks in a closed box suggests either that the cedar was already close to equilibrium, or that the box is not sealing well and the vapour is escaping rather than being absorbed. The lid should be checked in that case before cigars are trusted to it.
Switching to storage level
Once seasoning is complete, the 84 per cent pack has no further role and should not be left in with cigars. It is rated for preparing wood, not for keeping tobacco, and it belongs to a different job. Replace it with packs at the level you intend to maintain — 65 or 69 per cent for most collections, 72 for long ageing — using one size-60 pack per twenty-five cigars or so, and a little more for a box whose seal is only adequate.
Do not mix the seasoning pack with storage-level packs in the hope of a gradual transition. Two ratings in one space work against each other and both exhaust faster. The change should be clean: seasoning pack out, storage packs in.
Seasoning a box that has dried out
The same process applies to a humidor that has been neglected. A box left empty over a summer, or one whose owner stopped replacing packs, will have dried back towards ambient and will behave exactly like a new one when refilled. The difference is that it may already contain cigars. In that case the cigars should come out, be stored temporarily in a sealed container with a storage-level pack, and the box seasoned empty. Reintroducing them before the cedar is satisfied simply repeats the original mistake.
A fortnight well spent
Two weeks feels like a long time to look at an empty box. Set against the years the humidor is expected to serve, it is nothing, and the alternative is a first month of falling readings and tight wrappers. Season the box, not the cigars. Give the cedar what it needs from a pack designed to give it, and by the time the first cigars are laid in, the wood will be a partner in keeping them rather than a competitor for what they hold.