If I remember correctly CO2 is heavier than O2 and will
settle out with the oxygen above it. Within reason will
the small quantities of CO2 created near the end of
fermentation protect the wine from oxidation?

I realize that the movement of a carboy or uncorking
in general will enter eddies in the air within the carboy,
allow some mixing of CO2 and O2 and also allow some
O2 to enter but would the CO2 quickly displace the oxygen
over the wine and protect it.

I not looking for guarantees here but an answer to something
like, if I open my carboy then replace the airlock would
giving the wine a quick swirl to release some dissolved
CO2 help to protect the wine from oxidation?

Don

"Don S" > wrote in message
om...
> If I remember correctly CO2 is heavier than O2 and will
> settle out with the oxygen above it. Within reason will
> the small quantities of CO2 created near the end of
> fermentation protect the wine from oxidation?
>
> I realize that the movement of a carboy or uncorking
> in general will enter eddies in the air within the carboy,
> allow some mixing of CO2 and O2 and also allow some
> O2 to enter but would the CO2 quickly displace the oxygen
> over the wine and protect it.
>
> I not looking for guarantees here but an answer to something
> like, if I open my carboy then replace the airlock would
> giving the wine a quick swirl to release some dissolved
> CO2 help to protect the wine from oxidation?
>
> Don

Hi Don,

Heavy gasses do not settle out of a mixture of light and heavy gasses.
Quite the contrary. At temperatures above absolute zero, molecular motion
causes gases to mix automatically.

Gases can help reduce wine oxidation, but they must be used with care.
Please read what Clark Smith has to say about blanketing wine with gasses
here http://www.vinovation.com/ArticleArgon2.htm

Regards,
lum

>
> Heavy gasses do not settle out of a mixture of light and heavy gasses.
> Quite the contrary. At temperatures above absolute zero, molecular motion
> causes gases to mix automatically.
>
> Gases can help reduce wine oxidation, but they must be used with care.
> Please read what Clark Smith has to say about blanketing wine with gasses
> here http://www.vinovation.com/ArticleArgon2.htm

An interesting read Lum but in this section:

THE MYTH: Carbon dioxide blankets wine.

THE FACTS: Although substantially heavier than air (44 vs 29 MW),
the turbulence with which this gas is introduced into a headspace
through a 1/4" line results in substantially mixing. Dry ice works
much better, but sets up a worse problem: headspace CO2 dissolves
rapidly into wine, imploding the tank unless a vacuum relief valve
(almost always) invisibly allows air to be sucked in.

I find it curious that they say that the turbulence with which it is
introduced is a problem and then they go onto introduce their own
preference, argon, with out any problem. If argon can be introduced
slowly than so can carbon dioxide. However I can see their point on
it being dissolved back into the wine.

They do say that carbon dioxide is heavier than. Therefore it would
seem that carbon dioxide could be used to blanket the wine except for
the mentioned problem of having it dissolve back into the wine. This
would not be a problem in the case I am thinking of as it's right
after fermentation when the wine is full of CO2.

Thanks for posting the article.

Don

Lum,
Interestingly in the way that Google Groups works, my posting
was lumped together with another thread on the same topic
from 1999 where you were discussing that exact item. No time
to read it now as work calls but it should be an interesting
read later.

BTW, I know it's been said before but perhaps not by me, thanks
for hanging around this newsgroup and giving us help with our
habit... I mean hobby.

Don

Don S ) wrote:
>>
>> Heavy gasses do not settle out of a mixture of light and heavy gasses.
>> Quite the contrary. At temperatures above absolute zero, molecular motion
>> causes gases to mix automatically.
>>
>> Gases can help reduce wine oxidation, but they must be used with care.
>> Please read what Clark Smith has to say about blanketing wine with gasses
>> here http://www.vinovation.com/ArticleArgon2.htm

>An interesting read Lum but in this section:

> THE MYTH: Carbon dioxide blankets wine.

> THE FACTS: Although substantially heavier than air (44 vs 29 MW),
> the turbulence with which this gas is introduced into a headspace
> through a 1/4" line results in substantially mixing. Dry ice works
> much better, but sets up a worse problem: headspace CO2 dissolves
> rapidly into wine, imploding the tank unless a vacuum relief valve
> (almost always) invisibly allows air to be sucked in.

>I find it curious that they say that the turbulence with which it is
>introduced is a problem and then they go onto introduce their own
>preference, argon, with out any problem. If argon can be introduced
>slowly than so can carbon dioxide. However I can see their point on
>it being dissolved back into the wine.

>They do say that carbon dioxide is heavier than. Therefore it would
>seem that carbon dioxide could be used to blanket the wine except for
>the mentioned problem of having it dissolve back into the wine. This
>would not be a problem in the case I am thinking of as it's right
>after fermentation when the wine is full of CO2.

>Thanks for posting the article.

>Don


Gases really don't settle out by weight. At standard temperature
and pressure, a mixture of gases will be absolutely uniformly
distributed, even in the abscence of turbulence, because of brownian
motion.

In this sense gas is like a fluid--miscible liquids DO NOT settle
out by density or weight or anything like it.

That being the case, the only way to use one gas (Ar, N2, CO2) to
protect wine from another gas (O2) is to use the first gas to drive
out all traces of the second gas.

Which is what Tom was saying several posts back, :-)

Dave
************************************************** **************************
Dave Breeden

I think this is the relevant posting from that thread back
in 1999. Basically during active fermentation the CO2 will
act like a blanket but not afterwards. I would assume though
that as long as some CO2 is produced the bubbling of it through
the airlock will eventually displace the O2 and not let any
to re-enter. So the shake of a carboy to force some CO2 out
of suspension is valid just not sure how much would be required.

Second point is that the CO2 and O2 do not separate out but
wil mix in all but the most ideal situations, near 0 deg K
perhaps?

Don

-------

This is not an "equlibrium problem". It's a good example of "pseudo-steady
state". I don't expect that to mean much to most folks, but it realy says
it all. Or in plain english......

There are a few things that you need to consider. 1) The foam layer at the
top of the wine early in fermentation is nearly all CO2 (by volume),
there is no air in the bubbles that comprise this foam. 2) On a volume
basis the total amount of CO2 produced by the frementation of grape juice
is many times larger than the fermenter head space, this would be true
even if you used a plastic bucket that was only half full. 3) The system
is not static you are continuously introducing CO2 at the surface, in
order for O2 from the air to reach the surface of the foam layer it would
have to pass through a continuously moving front of newly formed CO2. As
long as there are no breezes accross the surface, this font of emerging
CO2 is enough to keep the O2 concentration very low close to the surface.
Thus the term "CO2 Blanket", but rather than being applied from above as
with most blankets it is regenerated continuously from below. So even a
loose fermenter cover is adaquate early in fermentation because it just
has to prevent air cross air breezes, the emerging CO2 does the rest. But,
even with a cross breeze, the foam layer would still offer a lot of
protection. 4) Finaly, the situation discribed in 3) is stable for days
because of 2). I knew I needed 2) for something.

Later in fermentation, the foam dissapears and CO2 generation slows enough
so that O2 can reach the surface of the wine by diffusion (diffusion = net
effect of random molecular motions, i.e. no breeze required) This is why
its important to rack into a container with a small headspace and an air
lock.

Finaly, everything in your discussion below would be true if the rate of
CO2 production was low enough as to be neglected. In such a case, the
entire head space would become uniform with the air above.