I normally use whatever is available at my LHBS when buying bottle caps, but understand the oxygen absorbing ones are recommended for lengthy bottling times (1 yr+). What do you your thoughts on this?
I am wondering how they absorb oxygen and to what degree/ timeline. The bag does not seem hermetically sealed so right of the shelf they have been exposed to oxygen.
Haven't noticed hop robbing quality but I don't make a lot of IPA.
I've only used them once or twice, but I do generally know how they work. They contain pure iron (or a similar metal), probably in rather small particles, embedded in a membrane. The basic principle is that when exposed to oxygen, the pure (zero state) iron will oxidize to form an iron oxide (with a higher valence state). This consumes oxygen and "traps" it in the metal.
They aren't "activated" until you wet them, my guess is there's some type of very thin water-soluble layer that dissolves away and exposes the metal particles to the air in the headspace. The reaction happens on the order of hours, so wetting the caps via a dunk in Star San right before you bottle will not negate the oxygen-absorbing properties.
Iron (and other metals) give off a tiny bit of heat as they oxidize, and this is how chemical hand warmers work. When you open the bag, you expose the iron powder to the air. As the iron slowly oxidizes, it produces heat.
The science behind the caps is pretty basic, but I don't know if it the result is anything noticeable.
I've only used them once or twice, but I do generally know how they work. They contain pure iron (or a similar metal), probably in rather small particles, embedded in a membrane. The basic principle is that when exposed to oxygen, the pure (zero state) iron will oxidize to form an iron oxide (with a higher valence state). This consumes oxygen and "traps" it in the metal.
They aren't "activated" until you wet them, my guess is there's some type of very thin water-soluble layer that dissolves away and exposes the metal particles to the air in the headspace. The reaction happens on the order of hours, so wetting the caps via a dunk in Star San right before you bottle will not negate the oxygen-absorbing properties.
Iron (and other metals) give off a tiny bit of heat as they oxidize, and this is how chemical hand warmers work. When you open the bag, you expose the iron powder to the air. As the iron slowly oxidizes, it produces heat.
The science behind the caps is pretty basic, but I don't know if it the result is anything noticeable.
The science behind the caps is pretty basic, but I don't know if it the result is anything noticeable.
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