Why do some wine bottles have indented bottoms?

In todays question for cecil, - http://www.straightdope.com/classics/a990305b.html - He states the reason for indented champagne bottles is to nestle the bottles during the process of making champagne the traditional way (fermenting in the bottle).

I was recently at a tour of a winery in BC that makes sparkling wine. They said the reason for the punt was that it makes wine bottles stronger for the high pressure incurred during the fermentation process. They said sparkling wine would blow the bottom out of flat bottemed bottles. Also when settling out the sediment their bottles were placed in racks with the bottle neck downwards from the start.

This same winery also beleives in pyramid power. They built a $800,000 pyramid and put all their product in it for about a month. They say independent taste tests indicate a definite improvement in the wine after being in the pyramid. They went further to state that knives will self sharpen if left in the pyramid. I have no belief in pyramids, but think the pyramid is a great marketing ploy if you do not sweat spreading ignorance.

Anyways, does anyone else know what the purpose of punts are in sparkling wine bottles? For nestling bottles, or to make them stronger to withstand pressure?

[Edited by bibliophage on 09-20-2001 at 07:07 AM]

How does the pyramid know to sharpen knives and make wine taste better, and not the other way around? I’ve never understood that.

Given the level of veracity of your source, I’ll go mostly with Cecil on this one. However, as a homebrewer/vintner, I do know that non-punted wine bottles aren’t strong enough to hold pressure, but that’s mostly because the people who put punts into the bottles also make them about 1/2 again as thick as regular glass. If you have refillable beer by the case in your area, compare a refillable bottle with a screwtop bottle. The refillable bottle is WAY heavier. They don’t have punts, either.

I think Cecil was a bit too flippant on this one. The punt wouldn’t fool anyone about the quantity of wine in the bottle; the volume is always indicated on the label.

The BC winery Mikemike visited was right (about the purpose of the punt, not pyramids); the punt makes the bottle stronger. The punt also provides a place for sediment in still wine to gather and it can serve as a thumb hold for pouring as well. Mostly, however, it’s just a tradition like natural cork, which people associate with high quality wine.

I can’t believe The Great One missed this. An important reason for those indentded bottoms that one finds in wine bottles and various other liquor bottles is as follows–

Winning bets in bars! It’s simple. You bet people that a one litre bottle actually holds more then a litre. To prove it, you take an empty bottle, fill it with water, then turn it over and fill the depression in the bottom.

(This scam courtasy P.G. Wodehouse.)

I’ve visited probably 12-15 sparkling wine producers in France and California. This question is almost always asked, or an explanation volunteered, on the tours. The most consistent response from the leading houses (e.g., Moet et Chandon, Taittinger, etc.) is that historically, the punt was needed to prevent the bottle from exploding. The idea was that the walls of the bottle, being circular in cross-section, are self-reinforcing, while the bottom, which on most bottles is flat, presented a weak spot. (I’ve always wondered why the walls would “self-reinforce” since the pressure is exerted from within the arc rather than from outside it, but I’ll leave that alone for now.) The guides generally explain that this was historically necessary due to inconsistencies in glass quality, but that advances in that industry have made the punt obsolete. It is now preserved out of tradition, and because waiters who prefer to pour sparkling wines while holding the bottom of the bottle place their thumb in the punt.

The older houses in France will often explain that the loss rate due to bottles exploding in the cellar has dropped dramatically in the last half-century, and the hazard of older bottles is evidenced by the woven wire wrist guards which were used at a time when the bottles were opened by hand after riddling was complete to remove the yeast plug. (Basically, riddling is performed to progressively move the sediment of dead yeast cells down into the neck of the bottle, which is then frozen and the yeast plug removed. The void, or head space, in the bottle is then filled with additional wine.)

In addition to the explanation written above which contradicts slightly that provided by Cecil, I wish to point out that the vast majority of sparkling wine produced today is riddled en masse. The bottles are cellared in large racks, and a special machine periodically comes through the cellar and riddles each rack. The punts serve no purpose whatever in machine-riddling, since the machine never handles the individual bottles. A very small quantity of sparkling wine is still riddled by hand (by persons called remuers). This is typically done either on high-priced vintage Champagne (e.g., wine destined to be Dom Perignon, etc.), or in Champagne houses where the cellars, carved from the chalk beneath the cities of Reims and Epernay, are too small to accomodate the machines. I’ve been fortunate to watch a human remuer in action-- they move incredibly quickly, and perform three actions (on two bottles-- one in each hand) in a blink of an eye: they turn the bottle slightly, increase its neck-down tilt slightly, and tap it gently.

I too have heard that the punt is for strength (actually, i think i read it in Isaac Asimov’s Book of Facts) and it makes the most sense to me. Too, if you’ll notice, all bottles, as well as glasses, bowls, plates, etc. have at least a slight depression on the bottom to allow them to sit flat without wobbling. Far easier to cast a depression than make a flat bottom.

As to why returnable (refillable) bottles are made of thicker glass: They actually expect to get them back. The thinner bottles are cheaper to make and are designed to be thrown away. The refillable bottles have to be strong enough to stand up to rough handling.

Fiat Lux,

Hey Mikemike2, which winery?

… and you wouldn’t be from Canmore, wouldja? :wink:

This extract from the Simi winery newsletter (1995) also mentions the indentation existing to help prevent exploding bottles.

Rob S.

Thanks for the replies:

Ethilrist- You make a good point about the pyramid knowing to improve the wine and sharpen the knives. They also stated it would preserve food (it would petrify instead of rot) and make white hair go back to its natural color. There were sleeping bags in the corners so people could sleep in the pyramid. Again I am a total skeptic in regard to all the claims and many of them could be easily tested.

Teach- I wonder when wineries will replace corks with are subject to infecting wine, with inert plastic corks which do not have this problem. From what I have read the old idea that cork allows a small amount of air in to help mature the wine is false. All of the maturing is done with the small amount of air trapped at the top of the bottle. I read that there are many wineries that would like to make switch, but they are scared their wines will then be perceived as cheap.

Octothorpe and Bvernia- Nice to see some fellow new posters :slight_smile:

Barbarian- The winery is Summer Hill. You are close, I live in Calgary

Hazel- That’s very funny.

So the consensus seems to be that the punt did have something to do with pressure (it may have had several uses), at least in the beginning of the bottle making process.

Because it’s magic, of course.

So? That’s a reason to depress the bases of sparkling-wine bottles, and only sparkling-wine bottles, by more than an inch?

And I can’t see it being structural strength, either. Maybe some combination of structural strength and the exact process by which the bottle is made. Or, rather, was made, once upon a time.

i had also always heard/read the “the punt provides structural integrity” theory, and started to post on this subject just yesterday. i decided to look for a cite first, and, well, wound up deciding that the issue was not exactly as straightforwards as i had thought and that, in retrospect, that Cecil had done a decent job.

i won’t bother posting all the conflicting cites i found, but this is a pretty good summary of most of the theories:


i still like the “adds structural integrity” theory best, though if called upon in a court of law to testify i would have to admit i have no compelling evidence and would just have to punt on the entire issue.

groaaaan. sorry.


ObTWIaVBP: the last “punt” reference is to american football, and unrelated to boating, betting, or wine

[pratchett] Pyramids don’t sharpen knives. They just take them back to before they were blunt. [/pratchett]

OK, maybe i added more information than was absolutely necessary. I probably should have mentioned the depression inherent in other bottles, china, etc. in another paragraph. I did not mean to infer that the punt was exclusively to allow the bottle to sit ‘flat’, although logically, that was probably a secondary consideration.

My reasoning:

A champagne bottle can be looked upon as a pressure vessel. A punt has more surface area than a flat bottom thus there will be less pressure per square centimetre on the bottom than if the bottom were flat. You could accomplish the same thing (i.e. increase the surface area, decrease the pressure) if you were to cast a hemispherical bottom, but then the bottle would not sit upright.

This can be seen in many pressure vessels. Air compressor tanks, propane tanks, steam vessels, etc. are generally spherical or, if they are tubular, have hemispherical ends. These are ‘ideal’ shapes in that they provide the greatest strength for the thickness of the material used and allow the pressure of the contents to be evenly distributed accross the entire surface of the vessel.

Originally, the plastic 2 litre soda bottles were extruded with a hemispherical bottom and a separate base had to be added to allow he bottle to sit upright. Present day bottles of this type have a modified punt to allow the bottle to sit upright and do away with the separate base.

Of course, this is only my opinion and like so many others, i will attempt to defend such opinion. In reality, i could be 100% wrong. To see myriad different views of the purpose of the punt, go to:

Fiat Lux,

They do use plastic, at least on the less expensive product. I am in the process of consuming a rather nice McWilliams Shiraz/Cab (under AUD $10) just now, and it has a plastic ‘cork’. Looks just like a ‘cork’ cork. Has the advantage that it doesn’t break during opening. Upmarket wines still have cork corks, generally composition cork with a solid cork end. Waste of money – it’s pure snobbery.

There was time when carbonated drink (ginger beer) bottles were indeed made like this. They had a glass ball as a stopper and a pointy end. Now highly valued collectables. People actually purchase rights to mine old gold field rubbish tips to search for them.

Except that pressure is already a “per square centimeter” quantity. If the pressure in the bottle is (to pick a random number) 100 dynes per square centimeter, then each and every square centimeter of the bottle would feel a force of 100 dynes, no matter what the shape of the bottle. The presumed strength advantage would come from the dome shape: A dome is very strong against pressure from the outside. The problem with this, though, is that any gains in strength over the dome itself would be lost where the edge of the dome meets the sides of the bottle. If part of the bottom would break through without the dome, then the whole thing would break off with it.

If it’s not something with stacking the bottles, as Cecil says, my guess would be that it’s the volume thing. Sure, all the bottles have the volume printed on the label. Don’t assume that people are overly rational, though. If one bottle looks bigger than another, it’ll sell better, even if they’re exactly the same.

Along this line, a sommelier friend of mine said since less surface of your hand is touching the bottle, just your fingertips and thumb, chilled wines will stay that way longer.

That may be true, but the punt increases the surface area, and so the bottle will warm up more quickly.

That may be true, but the punt increases the surface area, and so the bottle will warm up more quickly. **

I think that’s why ice buckets were invented?

How do you figure? Where the dome meets the side of the bottle, the glass is curved back around to form a sort of half-torus shape. Since the curvature in one direction is much tighter than the curvature of the dome, the transitional shape ought to be stronger than the dome.