They certainly can’t work by shoving air in like the coke ones

Because that would oxidise the wine.

I have a Coravin which injects a neutral gas (argon?) through the cork and allows wine to escape under pressure. So you can take out a glass of wine without removing the cork and without allowing any air in, so the wine is unaffected. It’s v clever.

Posted By: Old Git, Jan 24, 21:14:28