Thanks everyone! I had
@Drunkula's link bookmarked already, just never referred to it since I was using predefined carbonation drops and not sugar. Had I read it more clearly at the time I'd have been introduced to the concept of 'vols' as a measurement of carbonation. Just goes to show, you're never too old to RTFM.
It does sound however that there's a good amount of experience among forum members when it comes to over-carbing, and based on the above only
@Scrattajack had a potentially dangerous situation, possibly due to excess shaking when the bottle hit the floor and excess temperature when it came to rest near a radiator.
Now that I have my new unit of measurement I'd be interested in learning where the boundaries lie in terms of gushers and bottle bombs, i.e. when can I expect beer all over the floor, and when can I expect a face full of glass. My carbonation drops, confusingly, claim to be Sugar
and Glucose, and there are 80 of them in a 160 gram bag. So that's 2 grams of glucose per drop. Using the
priming calculator at Brewer's Friend I see that for a British Ale at 2.0 vols I need 2.3 grams of table sugar, which is a smidge more than one carbonation drop. The instructions on the back of the bag don't differentiate between styles of beer, they just tell you to add 1 drop per 350 ml bottle and 2 drops per 500 ml bottle. I've always added 2 drops for 500 ml and found that to be the bare minimum level of carbonation, any less and I'd call it flat. 2 drops is 4 grams and using the calculator that translates to 2.85 vols at half a litre, which actually puts my nearly-flat beer between American Ales / Lager and Fruit Lambic. That can't be right.
On the other hand, I've just used 2 drops per 330 ml bottle for my Wheat Tripel, and that works out at 3.9 vols, which is German Wheat Beer territory. I'd be happy with that, but given that my 500 ml bottles of ale have been borderline under-carbed at 4 grams I'm wondering if the Tripel will also be a tad restrained. Then again I did add more sugar and spraymalt at the beginning than I should have (another case of RTFM) so let's hope that all those sugars have fermented out. Might use gloves and safety-goggles just in case when popping one open in 8 weeks time.
Which begs the question: how many vols do you need to blow a bottle?
And do all crown caps have this safety feature?
(image from
Brewer's Friend)