low carbonation and capping

[Axel]

Greetings,
It's been 6 months from my first batch and 3 from my second one. In both batches some of those beers had good carbonation but most of them had a low carbonation. Before checking possible causes such as priming sugar, or no stirring in wort of that priming sugar, I would like check if capping might be the problem. The good carbonated beers had a strong pop sound when they where opened. Low carbonated beers had a weak hiss instead. In my opinion, a weak hiss means there was indeed a tight seal because the CO2 could not get out of the bottle. Badly capped bottles have really flat beer and cannot retain any gas at all. I am right?. Thanks in advance.

 

[flars]

A seal which is not perfect could retain some of the CO2 for a certain period of time. The longer the time since bottling the less pressure retained.
Were these twist off cap bottles?

 

[Axel]

Flars, your description matches my results. No, they werent twist off bottles. They are re-used european beer bottles, mainly British Fullers and Belgian La Chouffe. I am using a bench bottle capper. I have not attached the bottle capper to a table so I have some movement and poor stability during the capping process. I wonder if that might causing problems.

 

[flars]

Flars, your description matches my results. No, they werent twist off bottles. They are re-used european beer bottles, mainly British Fullers and Belgian La Chouffe. I am using a bench bottle capper. I have not attached the bottle capper to a table so I have some movement and poor stability during the capping process. I wonder if that might causing problems.

I have some old Hacker-Pschorr bottles I collected in the mid 80s. When I cap them with the standard 26mm cap I often get an upward crease across the top of the cap. I think the crown on this bottle may be 25mm. I still get a good seal though.
Could it be the caps for your botttles are not a perfect fit. Another possibility is the bell of your capper may not be fitted well.
Movement of the capper could possibly be a factor. I fastened mine to an eight inch by 12 inch base. I then use a single screw to fasten this base to my work bench.
Experiment with both brands of bottles. Add some soda to each brand of bottle. Shake them well and hold under water for signs of escaping gas. It may be one brand of bottle is the culprit.