Why do wine bottles have a concave bottom?

October 3, 2024 10:26 PM

Why do glass wine bottles (and wine-bottle-shaped glass fruit juice bottles) have a concave bottom?

Is it

a) to help you get every last drop out?

b) to reduce the chance of the bottle breaking in transit?

c) to make it look as though the bottle contains more liquid than it actually does?

d) to make it easier to stack or pack bottles?

e) another reason?

posted by chariot pulled by cassowaries to Food & Drink (9 answers total)

You're looking for the word 'punt.'
posted by kickingtheground at 10:49 PM on October 3, 2024 [4 favorites]

In champagne bottles it's to reduce excess pressure on the glass and avoid breaking bottles. In some red wines, it provides a decanting effect, trapping sediments in the bottom of the bottle and I think overall, it gives bottles more strength.
posted by alltomorrowsparties at 11:33 PM on October 3, 2024 [2 favorites]

I'd always just assumed it was because glass is hard to 'blow' flat, and may sag as it cools. So making the base concave reduces any chance of it going convex immediately after manufacture (ie if they had made it flat).

So making it concave, helps ensure the bottle can stand upright.

On preview.. @alltomorrowsparties answer also makes sense!
posted by many-things at 11:35 PM on October 3, 2024 [1 favorite]

Seconding alltomorrowsparties' answer: I always heard that the bottles with a concave bottom were those whose wine is likely to have more sediment, helping to trap it somewhat. Still has to be decanted, but the bottom helps prevent the sediment from escaping.

I'm assuming the bottles with a flat bottom are cheaper or less dense wines, maybe, or perhaps they are modern bottlers with fewer arcane traditions?

Then again, wine lore is full of myths......
posted by Bigbootay. Tay! Tay! Blam! Aargh... at 11:43 PM on October 3, 2024 [1 favorite]

Soda cans also have concave bottoms. My assumption (without Googling) is that it helps to make it stronger, and ensures that it stands straight when placed on a flat surface without wobbling.
posted by snarfois at 1:45 AM on October 4, 2024 [2 favorites]

Punts most definitely have a purpose of relieving strain in pressure vessels. See answers and links here in this previous thread.
posted by SaltySalticid at 4:27 AM on October 4, 2024 [2 favorites]

Soda cans also have concave bottoms.

Soda cans (like champagne bottles) are under pressure. A flat bottom will tend to bow out - a concave bottom is like an arch, and is much harder to invert (though if you freeze a can of soda or get it too hot, that does happen sometimes). Also it's not really practical to make stuff exactly flat, and if it errs on the side of bowing out, (or if there's a piece of grit underneath it) then a vessel with a nominally flat bottom won't sit flat. That's why even drinking glasses or soup bowls tend to have a concavity in their underside.

I think the answer may be "there's a lot of benefits to doing this and not much (if any?) drawbacks"
posted by aubilenon at 9:04 AM on October 4, 2024 [1 favorite]

I've always thought the answer is B, structural integrity. This article sort of agrees but also suggests it's no longer necessary.

I like another explanation I found online: it gives you a place to put your thumb when pouring elegantly.
posted by Nelson at 9:34 AM on October 5, 2024 [1 favorite]

It's to aid decanting.

If the bottom is flat, any sediment will be spread evenly across the bottom. Tipping out the last of the wine will disturb the sediment, so you have to leave more in the bottom to avoid mixing the sediment with the last pour.

This issue is reduced when the sediment is confined to a smaller area.
posted by HiroProtagonist at 7:44 PM on October 10, 2024