Beer (extract-based English bitter) has been in bottles for 3 weeks at cellar temperature (~60-70 F) with very little carbonation occurring.
I can think of a few things I might have screwed up to get here:
Under-primed. I used the low end of the recommended amount of corn sugar because I do want this to be only lightly carbonated.
Old caps. Some of the caps I used were a few years old. Possibly they couldn't hold the pressure (but the plastic liners didn't seem any stiffer than the ones on some new caps I have).
Didn't allow my bottles to dry sufficiently after sanitizing in bleach solution and killed the yeast.
I'm thinking I'll have to pour all this beer out back into my fermentation bucket and let it sit for 24 hours to de-chlorinate. Then re-prime and re-bottle with new caps.
Is there any easier way to recover from this problem? Is there any other possible cause of the problem I didn't think of?
Update two weeks later:
It seems that some bottles have better carbonation than others. I guess this points to I might not have mixed the priming sugar syrup into the wort well enough before bottling.
There is enough carbonation in most bottles to cause some dramatic foaming if you drop in a carbonation drop.
After adding carbonation drops to a couple of bottles and waiting another week, there is still not much carbonation there (but maybe this is due to increased headspace in the bottles after adding the carbonation drops).