Great discussion here.
Theory and actuality are 2 different things. I’ve had wine oxidize while under vacuum with headspace as well. Despite the vacuum there’s gotta be other variables contributing to free so2 binding up to then allow for wine to oxidize- . I dont know what these variables are— but they exist. They have to.
I compare it to the natural vacuum created in barrels. The barrels natural vaccum is pulled continuously due to the porous wood’s o2 permeability reacting with the outside temp & pressure (? Or something along these lines). So a barrel’s outside factors actually help contribute to the vacuum.
A glass vacuum is just pulled and capped while outside factors fight to undo it.
I won’t say the headspace eliminator is flawed. It’s not. It’s a great product and does a great job. Its a fantastic temporary solution. the only way to make it long term would be a constant pull like what naturally occurs in barrels, rather than a pull & cap - which isn’t realistic to do. If that was actually figured out then you’d have the benefits of a barrels vacuum without the issue of so2 binding. Until then it’s temporary or topping up the vacuum routinely.
like
@Whyno pointed out, a comprehensive study of so2 levels before & after of glass topped up, glass with headspace w/ & w/o HE’s, & barrels would probably answer a lot of the unknowns.