The cork in a wine bottle, says Daedalus, is an extremely cunning invention. It exploits the simple fact that cork swells in high humidity. The inner end of the cork, sealing the airspace over the wine, is at well over 90% humidity. So once in place, the cork swells and seals the bottle perfectly.

Daedalus is now applying this elegant principle to paint. In rainy Britain, every exposed wooden surface must be painted to stop it rotting. But no paint is totally impermeable to water or its vapour. It merely slows the rate at which the wood takes up or loses water. This is useful because even in Britain it rains only 5% of the time. A coat of paint prevents the wood imbibing a great draught of water every time it rains, and keeps its water content in balance with the average humidity. This is usually low enough to discourage rot.

But Daedalus is going beyond such purely passive barrier films. His new paint will let water out much more easily than it gets in. It will be inherently porous; but, like cork, it will swell in high humidity, sealing its pores against the ingress of water. Conversely, in hot or dry weather it will shrink, and its pores will open to let water vapour out easily. It will be an active water-pump, keeping a wooden surface drier on average than the air around it.

DREADCO's ‘Pumpaint’ will combine air-polymerization and emulsion-paint technology. It will consist essentially of a suitable monomer dissolved or suspended in excess water. When the paint is applied to a wooden surface, its monomer component will set quickly. As its water later evaporates, the polymer will dry out, shrinking into a microporous film. In humid conditions, it will take up water vapour again and re-expand to a homogeneous barrier. This constant stretching and shrinking risks peeling it from the wood beneath. It will have to bind itself firmly by chemical reaction.

Pumpaint will lay to rest the humidity paranoia of British builders, joiners and carpenters. They will enjoy once more the craftsmanship and feel of wood, and the elegance of its products. The dour advance of PVC, whose only advantage is that it does not rot, will be halted. And many noble ancient houses, steadily sabotaged by their deteriorating woodwork, may yet be saved.

The Further Inventions of Daedalus (Oxford University Press), 148 past Daedalus columns expanded and illustrated, is now on sale. Special Nature offer: m.curtis@nature.com