[lucideer]

> the Guinness head means you're getting less than a pint of actual beer

I hate to be pedantic but pint being volumetric, you're still getting a pint, independent of density. Also - a nitrogen head doesn't dissipate, so you never get a gap.

I'm now curious though whether a nitrogen head is less dense than a CO2 head...

[ahartmetz]

It feels much denser, and I think it does dissipate... but slowly.

[lucideer]

I'm sure it dissipates eventually but I've worked at weddings collecting pints that were forgotten about untouched - it really is a very very slow dissipation.