CR-002Care & Keeping
Oils that feed the wood
Perilla, tung and the drying oils for timber: how an oil finish cures, how to apply one thin coat at a time, and when oil is the wrong answer.
Entry checked on · kept by the tally · ~3 min read
An oil finish is the least sealed finish there is, and that is the point. It does not sit on the wood as a skin; it soaks into the surface fibres and hardens inside them, leaving the wood still breathing, still able to move, but fed and protected. The file keeps three oils above the bench: perilla for the honest work, tung for the slower cure, and linseed for the jobs that accept it.
How a drying oil cures
These oils do not dry by evaporation but by oxidation: the thin coat takes oxygen from the air and polymerises into a hard, resin-like film inside the wood's surface. That is why thin coats are the only coats, a thick coat skins over at the top while the layer beneath stays soft for weeks. Wipe on, wait, wipe off the excess, wait overnight, and repeat; the finish is built in patience, not in thickness.
The order of the work
The surface must be clean, dry and finished to its final grit; oil magnifies scratches rather than hiding them. The first coat wets the wood deeply; each successive coat adds less and dries faster. Between coats a light scuff with fine paper or a grey pad knocks off the raised grain. The last coat is left lean, the cloth folded, and the wood left alone to cure before water is allowed near it.
Where oil is the wrong answer
Oil is not for standing water, not for the floor of a busy hall, not for the surface that must resist alcohol or hot pots. It is for the object that is handled: the spoon, the bowl, the tool handle, the arm of a chair, the top of a bench. Where a film is needed, the file says so; oil asks to be re-oiled, and the piece that is loved is re-oiled without complaint.
The oil that is not linseed
Perilla oil, from the shiso plant, was the Japanese drying oil for centuries: it cures faster than raw linseed and yellows less. Tung is the most water-resistant of the three and the slowest to give up its tack. Each has its paper; none is magic.
The surface that ages well
An oiled surface does not stay perfect; it records. The handle darkens where the hand goes, the top lightens where it is wiped, the end grain drinks more oil and tells you so. That is the finish working as intended: a surface that wears honestly and is fed again, rather than a skin that fails all at once and has to be stripped. The piece that is oiled once a year looks better at twenty years than it did at two, which no film finish can claim.
The tin keeps for years if it is closed well, the rag goes stiff and is thrown out flat, and the surface a year later is the proof of the habit.
The card, filed
Oil is the finish for the piece that will be touched: thin coats, wiped off, cured overnight, renewed when the wood asks. It never seals the wood away from the air; it feeds the surface that does the work.
