Are the bubbles in a glass of champagne really caused by the glass being dirty?

Question

I was watching TV the other night and Stephen Fry (really clever guy in case you dont know him!) was saying that the bubbles were actually caused by imperfections and dirt on the glass. Is this true and if so then why is normal wine not fizzy?

Answer 1

The bubbles are caused by two things:
1. Champagne (or, as it is properly referred to as, sparkling wine) is infused with carbon dioxide, at high pressure, which expands upon the opening of the bottle, creating bubbles.
2. The bubbles generally form along the sides of the glass where imperfections in the glass (all glass has imperfections, which is why it is glass and not crystal) allow the expanding gas to accumulate.

Thus, bubbles aren't caused by dirt, but do form where imperfections exist. Pouring salt into a glass of champagne or beer will also have the effect of creating bubbles by giving the gas a place to accumulate.

Answer 2

A dirty glass or one with many microscopic imperfections will accelerate the fizzing, but once opened to atmospheric pressure the solution is supersaturated with carbon dioxide and will degas naturally. This is an excerpt from the link below:

"The solubility of carbon dioxide gas depends on its pressure; it's
more soluble at high pressure. That is why when you release the
pressure you immediately make the solution super-saturated, and the
gas bubbles out of solution. The same thing happens when you open any
bottle of fizzy drink, especially if it is warm and if you shake it
first. However, in those soft drinks, the carbon dioxide is pumped
into the liquid under pressure, rather than being generated by
fermentation.

Once the cork has been released the champagne gradually loses its fizz
as the carbon dioxide escapes."

Answer 3

There is dissolved gas in the champaign leftover from the fermentation process (just like beer) and that gas wants to escape the liquid. The dirt and imperfections on the glass simply give the gas a good place to nucleate and form into bubbles.

Wine is not fizzy because there are differences in the fermentation steps and the types of bacteria involved.

Answer 4

Optimus got it right first. There's dissolved gas in the plonk that, given the chance, will come out of solution in bubbles. As soon as you pull the cork (release the pressure) it actually wants to bubble. You need that or there will be no fizz.

But getting a bubble started is tricky. The key is nucleation - the bubble needs a "nucleus" to form around. Tiny tiny air pockets trapped in microscopic roughness in the glass (or in dirt in the glass) serve nicely and allow the bubbles to form.

Same applies to beer - don't let a barman pour you a beer in a wet glass - less nucleation sites.

Same applies to rain - that's what "cloud seeding" is all about - chucking lots of powder into a cloud so that the water vapour - which is really keen to condense into drops but can't quite manage it - has something to nucleate into. It's a very marginal effect though, so isn't very useful in practice (and rain-stealing is nasty).

Same applies to boiling water. You can make a bowl with no imperfections, hence no nucleation sites, with a pan of mercury. You spin the pan so that the mercury curves up at the sides and forms a bowl shape, then pour the water into the curve. Then you heat it up (by heating the mercury) while it's still spinning. You can get the water way past 200 degrees C at atmospheric pressure without it boiling. But at this point it's really desperate to boil (way off equilibrium) so any tiny chance to nucleate will result in the whole lot going off in one big bang. 200C spinning mercury and steam explosion. Don't try this at home.

No really, DON'T try this at home.

Answer 5

For champagne, there is trapped carbon dioxide but not in normal wine. This is probably due to the processes involved in the frementation. Nextly, for the champagne to bubble like we see they need an surface with niclear site where minute bubble collect to form one big bubble and rise up. A dirty glass would provide with more nuclear sites acelerating the bublling. Thus the bubbly you see is either the glass not being clean or fibre form the bartender's cleaning cloth.

Answer 6

Champagne has a significant amount of carbon dioxide dissolved in it, like soda. That CO2 is what you see bubbling in the glass. When the pressure on the bottle is relieved, the CO2 starts coming out of solution, and it does so in the form of bubbles.

However! Bubbles, generally, will not form spontaneously without something to stick to. Mr. Fry was correct in stating that the reason we see bubbles in champagne is because they form preferentially on things like small scratches or other tiny imperfections in the glass, specks of dust, etc.

So, the reason your champagne fizzes is because it has a large amount of carbon dioxide dissolved in it. You see the fizz because imperfections in the glass allow bubbles to form. You don't need to worry about having a dirty glass every time you see bubbles in your champagne - even the cleanest glass will have some manner of tiny imperfections that will allow the formation of bubbles.

Answer 7

The bubbles are not CAUSED by the imperfections in the way you are thinking. There will be imperfections on the glass, but the gas is released when it bumps up against something. That is in any liquid. That something may be on the glass, but it may be another bundle of molecules of that gas which is already in the liquid.

Normal wine is fizzy, but it doesn't mean the glass is dirty.

Answer 8

Carbonated drinks have a high amount of dissolved carbon dioxide. If there were imperfections or dirt in your glass, it is likely that you would see more bubbles at these surfaces, but you would still see the bubbles in a perfectly clean bottle as well. Opening the bottle (releasing the pressure) causes the carbon dioxide to come out of solution. Thus you see the bubbles being released.

Answer 9

There may be some true to your statement as the champagne does have carbonate in it. It is possible the the imperfections and dirt on the glass cause the carbonate to disolve in the liquid and bubble to the surface of the liquid and evapourate from the glass.

Answer 10

Stephen Fry is very clever indeed. And funny too, he was kidding m'dear.
During the fermentation process, carbon dioxide is released. When making regular wine, the CO2 is allowed to escape, so the wine isn't fizzy. When making champagne the CO2 is kept making it fizzy like any drink with CO2 (soda, Coke ext.)