The bottle you carried out here is warming up. There is a procedure for that.

The first warm weekends of spring send everyone outdoors: the park, the river, the boat, the campsite. The wine comes along; the fridge does not. The Handbook treats this the way pilots treat a warning light: not with panic, but with a protocol.

First proper warm Saturday of the season. A picnic rug in the park, the back of a boat, or a fold-out table at the campsite. The rosé came out of the fridge at home cold, but that was an hour and a car trip ago.

You open it and pour the first round. Everyone says something nice about it. Then the bottle goes down on the rug, the sun keeps working on it, and by the second glass someone asks the thing nobody wants to ask: "Is this still cold?"

Wine does not go warm all at once. It goes warm from the outside in, and faster than you think. A bottle is a thin glass wall with a lot of sun on it, and out here there is no fridge to put it back in.

• The esky. Works until it doesn't. By mid-afternoon it is a bag of cold water, the label has peeled off, and everything comes out wet and sandy. It also weighs more than the rest of the picnic.
• Ice slush in a plastic bag. The esky without the esky. Cold for a bit, then a puddle in the boot and a bottle you can't hold without a tea towel.
• The wet tea towel. Old bush trick: wrap the bottle, let the breeze do the work. It slows the warming a little on a dry day, and leaves you holding a wet tea towel.
• Buried in the sand, or dunked in the river. Cooler than the air, which is the only bar it clears. The Handbook has records of tide, ants, and one bottle that was never seen again.
• "Drink it fast." The most common response on file. Warm rosé is a different drink, and you did not carry it all the way out here for that.

Every one of these attacks the problem from the outside of the glass, or not at all. The wine, inconveniently, is on the inside.

The idea is simple: put the cold inside the bottle instead. Steel carries cold far better than glass does. A deeply frozen steel rod down the neck sits in direct contact with the wine, the full depth of the bottle, with no glass wall in the way.

And because the cold works from inside the bottle, there is nothing to carry but the bottle and the rod. No esky, no ice, no power point. That is the whole trick.

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The recommendation is simple: put one in the freezer before the first long weekend of spring, and the bottle stops being a problem you carry around. With Buy One, Get One Free, the second kit goes in the bag of the mate whose esky is a bag of water by three o'clock.