• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Oxy Caps



I have never used oxy caps before but I was considering some for my next competetion entries.

My question . . . if they activate when wet, how do I sanitize them before bottling?

AND are they really worth it?



I use oxygen-barrier caps all the time. I don't sanitize them. I keep them in a clean ziplock bag, and when I bottle I just take them out one or two at a time until I'm done. Then zip the bag and they sit on the shelf until next time I bottle. I've never had a problem.

The question of are they worth it is less clear. If you bottle a lot of long-lasting beers, or beers that need long aging, then I think they're worth it. The caps are not a major expense, and a penny more per bottle for potential benefit is worth it to me. I use them for everything just because I don't want to bother having two different caps laying around. Whenever I order something from the States, I add a pound of caps to make sure I have a supply, and that works for me.  ;)

One more point, there are really two different kinds of caps that people refer to as O2 caps. One is Oxygen Barrier caps, where the liner forms a better seal so less oxygen can slip through after the beer is capped. The other is Oxygen Absorbing caps, which actually soak up any oxygen that's in the head space. From what I've been able to tell, most caps sold in homebrew shops are the Barrier caps, not the Absorbing caps. If you can find real Oxygen Absorbing caps, those are the best for long-term storage!


Staff member
Grandmaster Brewer
Apr 5, 2003
Reaction score
I also used Oxy caps for many years, and I did not sterilize them either.   I do think they are worthwhile if you plan to store the beer for a while or are one who does not drink the beer that fast.  In several cases I've stored beers for well over a year at room temperature and they still tasted great when opened.