There might be a good reason for argon vs CO2; I'm not a wine guy.

But note that re: safety, if you need an inert gas, CO2 is usually your safest option. Why? Unlike other inert gases, you have a decent chance of detecting CO2 intoxication. For most people, excess CO2 is very unpleasant, giving you a chance (NOT a guarantee!) to recognize the hazard and escape. Meanwhile, if your body is short of oxygen because an inert gas leak has reduced O2 concentrations in the room you are in, there's a very good chance that won't notice and at some point will just pass out suddenly and die. Our bodies just don't have the ability to detect a lack of oxygen directly; we evolved to detect an excess of CO2 instead.

Now, I don't want to fear monger: you can certainly handle nitrogen and argon safely with some care and common sense. I myself used to work with liquid helium in large enough quantities to need an O2 alarm. But all things being equal, I'd use CO2.

> CO2 is usually your safest option

People with COPD need not apply.

CO2 intoxication is unpleasant for us because the baroreceptors in our arteries can detect when the partial pressure of CO2 is too high. This is the feeling you get when you hold your breath. You have somewhere between four and ten minutes of oxygen supply in your blood, but it becomes unpleasant within the first minute because CO2 is building up instead of being exhaled.

People with COPD always have an abundance of CO2 in the bloodstream because their alveoli don't exchange gases correctly. They likely wouldn't be able to tell the difference.

Just saying. Your argument is sound and generally true, but it's true not for everyone.

Helium is lighter than air, argon heavier.

Important safety difference. You'd still need to be careful, but unless you're lying on the floor...

Dangerous safety strategy if you have toddlers... Or pets, I guess.

Co2 will carbonate the wine.

It takes a fair amount of pressure or reduced temperature (or both) to get enough CO2 dissolved for the resulting beverage to be noticeably 'sparkling' (Source: Friends force-carbonating home-brewed beer in a keg (in a fridge) w/CO2 cylinder). Don't think it would happen much from just filling the air space with CO2 at room temp and pressure.

Sticking dry ice in a drink will make it taste noticeably carbonated. This is 1 atm of CO2 at the freezing point.

(Carbonating to 1 atm does not produce much fizz — it only produces any at all because the CO2 offgasses as the drink warms, but bubbles and the taste of carbonation are different phenomena.)

You’re being downvoted, but this matches my experience. A depleted can of CO2 gas produces weak carbonation, similar to dry ice.

One of the tricks to CO2 canisters is that CO2 liquefies around 6 atm at room temperature, so a canister of CO2 will maintain that pressure until the liquid CO2 is depleted. Dry ice produces about 1 atm of vapor pressure (obviously) which matches the vapor pressure you get when displacing air.

CO2 will acidify the wine, which might well alter its taste.

Carbonation (in the sense of making the wine fizzy) will not happen unless pressure is used to drive the CO2 into the wine. You need a supersaturated CO2 solution to get fizzies.

What kind of source is not pressurised? SodaStream (and other brands) work exactly this way, there's nothing fancy in the box, it's just a button letting gas out of the canister.

It's not about the source; it's about the application. The intention with wine is to let gas layer in the bottle, not introducing it into the liquid directly.

I have a SodaStream for making seltzer. I also use it to put a 'float' of CO2 in bottles that I want to last longer.

Simply, I put a bottle under the SodaStream nozzle and give a few puffs of CO2 to be confident that it's displaced most of the air.

I do this with normal drinking wine sometimes, but more often things like vermouth that I don't open daily.

> Why argon instead of CO2

Argon is a bit less soluble in wine. But both are used by professionals.

Given a free choice, I chose the heavier argon. I'd seen it in use in an SF wine store where one could try fifty wines. (An obsessive friend showed me this store. I have better follow-through.)

It is said that CO2 can carbonate your wine. If you haven't experienced this, you're fine. I know no reason to actively prefer CO2 to argon, if one is making a free choice.

CO2 will not carbonate your wine unless you pressurize it.

1atm of (normal air) displaced by 1atm of CO2 is not going to lead to any carbonation ...

Which store, if you wouldn't mind me asking?

Argon is better at reducing oxygen ingress in the short term, less than 2 weeks. But only strictly as a measure of dO2, sensorily a panel of experts were unable to determine the difference. So I would choose whichever is cheaper.

why not nitrogen?