Low bottle carbonation issue?

[DethApostle]

Morning all,

I've been brewing for around 6 months now however my last two batches have been barely carbonated when i've come to open them. There is definitely 'some' carbonation and I wouldn't describe the beer as 'flat', however it is difficult to get a head to form even when upending the bottle and pouring vigorously! I suspect it's just that i'm not adding enough sugar however I thought i'd ask here to see if there might be something else causing this problem!

I bottle pretty much straight from taking the FV out my fridge (from cold-crashing the brew) and individually prime each bottle with half a teaspoon of granulated sugar. The bottles are capped and then stored in a dark box inside the house at c. 20C for 4 weeks.
I also recently did an experimental batch with 6 different sugars and these also only came out part-carbonated, however the first 2 batches i made also used this method and carbonated ok.

I'll be switching to batch carbonation on my next brew now i had a bottling bucket, but other than the quantity of sugar is there anything other factor or element missing from my process above that would have this effect?

Thanks
DA

 

[winelight]

There's a thread on what a "teaspoon" actually means in one of the other forum areas. With granulated, a level teaspoon (depends on the size of your spoon and how much you fill it, of course) could be far less than you think.

Did you give the bottles a vigorous shake after capping?

Also in this cold weather I doubt my beer is stored at the 20C I think it is. It's on the floor, so will be quite a bit colder, and of course the house is not heated to 20C round the clock, if at all. Stored against an outside wall, or in a cupboard, would also be quite cold.

Bottom line - add more sugar :)

 

[Dunfie]

Probably just a lack of priming sugar.

How does it taste? If it is a little sweeter than expected then it hasn't fermented out properly.