Adding inert gas when bulk aging

Question

When I make my wines at home, I usually make it in roughly 13 gallon batches. However, after racking I usually lose about half a gallon to a gallon, so I have a fair amount of headspace in my container when it is time to age and clarify.

So far the longest I have bulk aged my wine was up to a year with no real issues. However I was recently given a much larger food safe plastic container to bulk age in. Since it does not have an airtight seal like my carboy, I am concerned about oxidation.

I am aware that CO2 is heavier than the air around us, so my question is a 2-parter:

1- If I add an inert gas like co2 to the container before racking and add the lid (Not really airtight) would this be enough of a seal to keep oxygen away from my aging wine?

2 - If this would work, how would I go about adding this inert gas?

Answer 1

Inert gas (provided it's heavier than air and is not water-soluble) will protect the contents of the vessel from the top, i.e. it will blanket the surface. It will not prevent oxygen ingress through the vessel walls, though. Therefore such aging should ideally take place in glass or stainless steel and not in polypropylene or polyethylene.

Adding the inert gas would best be done by having two valves set into the lid of the vessel; one to allow the gas to enter under slight pressure, the other to allow the oxygen to escape (i.e. being flushed out). Then close both valves.

Note that CO2 will over time dissolve partly into the liquid, thereby making it slightly fizzy and reducing the amount of CO2 gas covering the liquid. But in a closed vessel it won't matter if the protective gas is heavier than air or not, once you flush out all the air. Nitrogen could be a good option here. It is often used as an inert filler gas in hermetically closed packaging.