Incomplete Barrel Fill

Just thinking quickly off the top of my head: boil some extract with a little of the same hops that are in your original recipe, or get a bunch of marbles, sanitize them and add as a filler.

 

You can always top it off with bourbon

 

Do you have the capacity to purge the barrel with CO2?

 

I wouldn't necessarily worry about it. You're not doing a very long soak, so you're not really running risk of anything getting introduced, and you can basically let your beer and the freshly drained barrel do most of the work for you.
If you can. Purge with some c02 before you run it in, and use the freshly drained goodness to your advantage. If you cannot. You could also put it in a right before terminal and plug it so the beer creates the blanket for you.

 

This is certainly another option. As long as the beer is creating CO2, you're pretty safe with a little headspace if you're only aging for a short period of time.

 

You likely will be OK but it comes down to how much you are concerned about about 0.5 gallons of air (oxygen)/oxidation.

Cheers!

 

The CO2 layer theory is a false one. Oxygen exposure has to do with vessel permeability, so while having CO2 instead of air in your barrel before filling it with beer is decidedly a good thing, making sure your vessel is properly sealed is even better.

 

Sure, you can do whatever you want to. But. Honestly. Don't overthink it. I'll suggest (again) rack it over a few points above your suggested final, and let the yeast take care of creating the c02 for you.
Also, at six weeks, there's probably going to be enough low level work still being done by the yeast that they'll probably handle it quite fine if you bung it up and ignore them.

 

You can also wax the top of your barrel to slow oxygen ingress in the area where there is empty head space.

 

I've never used a barrel, but this approach makes the most sense to me. The reason a partially-empty barrel is so permeable is that the staves dry out. With your approach, I would guess that oxygen ingress would be substantially reduced. Maybe not all the way down to "full barrel" levels, but probably low enough to achieve your goals. Anyway a barleywine is meant to be a bit oxidized, if anything I would expect this to speed up the aging process.

 

Ehh . . . sort of. If a barrel is properly constructed and sealed, the staves and heads will stay wet via capillary action.

 

Could you expand on this?

I'm probably going to be transferring my keeping porter into secondary soon, with most of it going into a BetterBottle type carboy with Brett, and the leftovers being put in regular bottles with nowt. It'd probably be simpler to prime the whole lot and treat the carboy as an extra big bottle rather than try to do two separate operations. In principle I can see how a quick extra burst of fermentation after transfer would also help to mop up any oxygen that gets picked up on transfer and to flush any headspace in the carboy, but I'm not sure whether this is actually significant in practice... any thoughts?

 

Oxygen exposure is, essentially, diffusion though a semi-permeable membrane. In any vessel you have CO2 getting out via the airlock and the closure and air getting in via the closure, but also through the vessel walls in some cases. A certain percentage of air is oxygen. The headspace is always looking to achieve an equilibrium with the air outside of it, even though that isn't going to happen. That's basically how it happens.

As to your porter question, why not just measure how much porter you are going to bottle and made a priming solution? Although the extra bit of CO2 production might help, it also might change the character of your beer. Either way, I feel that the change would be miniscule and as long as you have good racking practices you should be just fine.

 

To address what I think might be @Dave_S's question, what @EvenMoreJesus meant when he said "The CO2 layer theory is a false one" is that all gases will, after a short period of time, reach an equilibrium in which they are evenly distributed. Heavier gases don't form a "protective layer" within a vessel. (The equilibration doesn't happen instantly, which is why the Lake Nyos disaster could happen, but it happens quickly enough that you can't count on a layer of CO2 to protect your beer for long enough to matter.)

But that's just to debunk a myth about the "layering" of gas. Excluding oxygen from the headspace of a fermenter is still an effective strategy. So the next question is how best to accomplish that, and whether it matters very much. I don't have a strong view as to "priming" the porter that you intend to age. I do think that priming would probably prevent some oxidation, both by encouraging the yeast to use oxygen and by "scrubbing" oxygen from the headspace as CO2 leaves solution. But I agree with @EvenMoreJesus that the effect would probably be minor. This is especially true as Brett is a good oxygen scavenger, so I would expect it to do a pretty good job eliminating the oxygen on its own.

By the way, just so you know, a lot of people from the U.S. use these forums, and some of us don't know what "nowt" means. I assume it means "nothing"? Is it a variant of "naught"?

 

Thanks folks - that all makes sense. The temptation to prime the whole lot is partly because I don't have a measuring thing the right size (I've got very minimal kit, for reasons of space), and partly because it removes any unnecessary thinking from the process by turning it into an exact repeat of my usual bottling process but with one bottle happening to be massive.

And sorry, yes, "nowt" is a British regionalism for "nothing" as in "bread wi nowt taken out", which I should probably have realised was a bit obtuse for an international forum...

 

One of these days I'm going to find a chemist or physicist whose math chops are up to the task and collaborate on an article entitled "The Myth of the CO2 Blanket."

 

It's called a CO2 blanket...not a CO2 impenetrable force shield for a reason