Ullage - What Exactly Causes This?

I'm assuming a secure cork and no strange handling etc.
All (or most) of my bottles also have a very secure foil (such as lead, aluminum or plastic) which are almost always tight (and often a pain to remove) so are seemingly airtight.
So why does the level in a bottle drop over time?

NOTE: I also have 30+ year old bottles which do not appear to have ullaged - they are still at a 'mark' (which may be sediment) inside the neck of the bottle.

Corks vary in their gas and liquid vapour transmission. I think it's as simple as that.

I'm assuming a secure cork and no strange handling etc.
All (or most) of my bottles also have a very secure foil (such as lead, aluminum or plastic) which are almost always tight (and often a pain to remove) so are seemingly airtight.
So why does the level in a bottle drop over time?

Evaporation -- there is no other choice. Once you accept that, you have to accept that liquid and/or gas is making it past or through the cork and capsule (this latter is no barrier, no matter how tight it may seem; I think that the original intent was to place a lead capsule on the bottle to discourage rats from nibbling on corks)

NOTE: I also have 30+ year old bottles which do not appear to have ullaged - they are still at a 'mark' (which may be sediment) inside the neck of the bottle.

Corks vary wildly in the tightness of their seal and integrity. Part of the difference, I find, is that corks that are coated with wax or silicone seem to hold a better seal and degrade more slowly. Beyond the issue of cork taint, this is another reason that I am in favor of alternative closures for wine: bottle variation in older wines is a huge issue.

Mark Lipton

[quote="Mark Lipton
Evaporation -- there is no other choice. Once you accept that, you have to accept that liquid and/or gas is making it past or through the cork and capsule (this latter is no barrier, no matter how tight it may seem; I think that the original intent was to place a lead capsule on the bottle to discourage rats from nibbling on corks)
Mark Lipton[/quote]

So liquid evapourates through the cork AND through the foil???
That seemed unlikely to me - hence my question. That's why I didn't accept it.
Not that I've ever put a lead seal over a beaker of water and left it for 30 years!

So could we, in theory, find a non-permeable membrane that would seal the bottle?
And how does lead stop X-rays but not water?

Evaporation -- there is no other choice. Once you accept that, you have to accept that liquid and/or gas is making it past or through the cork and capsule (this latter is no barrier, no matter how tight it may seem; I think that the original intent was to place a lead capsule on the bottle to discourage rats from nibbling on corks)
Mark Lipton

So liquid evapourates through the cork AND through the foil???

More likely, it perfuses around an imperfect seal and then evaporates and passes as a gas around the capsule.

That seemed unlikely to me - hence my question. That's why I didn't accept it.
Not that I've ever put a lead seal over a beaker of water and left it for 30 years!

It's notoriously hard to seal any container well enough to prevent gas exchange for years. Sealed ampules do the job, and a ground glass joint lubricated with vacuum grease also has the potential to do it, as do the pressure seals used in compressed gas cylinders.

So could we, in theory, find a non-permeable membrane that would seal the bottle?
And how does lead stop X-rays but not water?

Yes, PTFE (Teflon™) membranes will prevent gas diffusion if sufficiently thick (if not, you get Gore-Tex, which permits the diffusion of water vapor and oxygen but not liquid water). If I recall correctly, Stelvin closures have a PTFE liner to improve the seal. Crown caps also use some form of polymer to improve their seal. As for the X-ray vs. water comparison, it's apples and oranges: X-rays are stopped by lead because of its high density (increasing its cross-section to electromagnetic radiation), whereas water vapor can travel around the lead capsule because it's imperfectly sealed to the bottle.

Mark Lipton

I can possibly accept "around" the capsule. That seems more logical.
Having said that, a few years back I recall opening 6 bottles of an unclassified 1928 margaux for a tasting - where we discovered that 2 of the 6 didn't even have a cork (no it hadn't dropped in). And all levels were 'acceptable' - certainly no indication that the cork wasn't there before opening.
That suggests a pretty tight 'foil seal' - the wines had been stored on their side for several years prior to opening. But of course, 'vapor' can escape where 'liquid' can't get through.
So now I'm wondering if the cork really serves any useful purpose!!!!!!

What condition were the two wines in?

Salute

Regarding the 30+ year old bottles, I'd guess that the cork is longer in these bottles as they often are in wines that the maker intends to be aged many years. The longer the cork, the reduced chance for noticeable evaporation, I'd guess.

What condition were the two wines in?

Salute

Astounding!
This was a blind tasting of 8 wines from the Margaux commune.
The 28 came TOP!
I guess lead adds a little "je ne sais quoi" to the flavour.

What condition were the two wines in?

Salute

Astounding!
This was a blind tasting of 8 wines from the Margaux commune.
The 28 came TOP!
I guess lead adds a little "je ne sais quoi" to the flavour.

Well, you didn't need all those brain cells anyway!

I though it was aluminum foil that affected brain cells.
Doesn't lead concentrate elsewhere (? kidneys).
Anyway, as an organizer, I made sure I got a sample from a corked bottle (I mean one with a cork). Each bottle served around 20 people, so nobody keeled over!
We'd never let a 28 Bordeaux go to waste!

I can possibly accept "around" the capsule. That seems more logical.
Having said that, a few years back I recall opening 6 bottles of an unclassified 1928 margaux for a tasting - where we discovered that 2 of the 6 didn't even have a cork (no it hadn't dropped in). And all levels were 'acceptable' - certainly no indication that the cork wasn't there before opening.
That suggests a pretty tight 'foil seal' - the wines had been stored on their side for several years prior to opening. But of course, 'vapor' can escape where 'liquid' can't get through.
So now I'm wondering if the cork really serves any useful purpose!!!!!!

I believe that Bill Spohn had a similar experience with an uncorked bottle. In all likelihood, the wine dried out in the space between the foil and the glass, thereby completely sealing it. In fact, those old lead foils react with wine to form lead acetate, a white powder that would have been deposited in the space between the foil and the glass. (Lead acetate is also quite toxic) Keep in mind that there's a selection process going on: if the foil had been a less-than-perfect seal, it would've leaked from the start and never made it into anyone's cellar.

Mark Lipton

In terms of ullage, nothing to add to earlier posts.

However there is one other factor that affects the level of the wine when you dig it out the cellar - the level it was bottled with originally, which can vary immensely (indeed within batches of the same wine). Musar for instance tends to have quite a low fill. It's possible that an upper shoulder wine may have suffered less ullage than a top shoulder wine!

Question for Mark-
Wouldn’t “lead contaminated” wine taste “sweeter”?
(Thanks in advance Mark, for putting up with me).

Salute

Question for Mark-
Wouldn’t “lead contaminated” wine taste “sweeter”?
(Thanks in advance Mark, for putting up with me).

Salute

Yup. Lead acetate is supposed to have quite a sweet taste, though as you'll understand I've never verified that through firsthand experience. I don't know how the tasting threshold compares to its LD50 though.

Mark Lipton

A couple random thoughts:

Lots of wines when bottled have "spinning capsules"- if it can spin, it certainly isn't airtight.

I always think that those who proclaim loudly that only cork can offer proper aging should explain if they'd prefer a neck, VHS, or midshoulder fill on a 40 yr old wine.

Does anyone know the last dates for lead capsules? I generally follow idea of 1990 for careful wiping, but not sure if that is accurate.

I'll point out another reason why wine can evaporate through a capsule: by design, they're generally not air-tight. If you look closely, capsules of all materials almost universally have two or three small holes in the top. That's because without the holes they are difficult to put on the bottles. Even before they are "spun" onto the bottles, the fit of capsules is often sufficiently tight that there is significant air compression under the capsule during installation, making the process difficult. So even disregarding the fact that even a tight capsule can be pentrated by gases, virtually all capsules are intentionally leaky.

There is also a mechanism that might create ullage other than evaporation that I don't think anybody has mentioned. That is that wine can be absorbed by the cork itself, air spaces in the cork being replaced by wine over time. I suspect that evaporation is probably the biggest culprit and as in the case of evaporation, this would vary wildly by individual cork, but it seems possible that what was air space within the cork might become airspace between cork and wine with time.

Dale wrote;
Does anyone know the last dates for lead capsules?

I’ll have to agree with your guess early 1990s.
As far as ullage levels in 40 plus year old wines, it depends upon the wine. It’s hard to evaluate an older wine just by its ullage level (unless of course there is a tell-tale sign of leakage).

Salute