Gone Flat 6 Months After Bottling

[Martin]

This weekend I tried some beer I'd saved from a couple of brews I did 6 or 7 months ago. The beer has gone flat and I think it may look a bit darker than it used to be. When I originally drank the beer (2 months after bottling) it had the right amount of fizz. Could it be that the caps were not quite tight enough? The beer is in brown glass longnecks and has been stored inside a dark cupboard at roughly 20c.

 

[pint of lager]

Have bottled many many brews and the only time the beer was flat was when I used one of those nasty wooden hammer operated handcappers and hadn't put the caps on fully. This was many years ago. Bought a Superautomatica bench capper and have never had a problem since, even with twist top seals.

Are you sure the bottles were primed?

Could someone have interfered with the bottles?

The fact that you think the beer is slightly darker may mean it has oxidised, although trying to judge colours can be dicey.