Bottle Pressure Limits

[Chalkyt]

Going off at a slight tangent but just to add to my earlier post, I heat pasteurised a couple of batches yesterday and kept watch for any bubbles from under the caps. Sure enough, there was the odd bubble (about one per second) from one or two bottles.

Those batches were carbonated to 2.2 vols (2.2 bar or just over 30psi). I used a souse-vide heater to hold the bath at 65C so by the time the bottles had reached 64C (after about 10 minutes in the bath), enough pasteurisation had taken place. The bottle pressure reaches just under 90 psi at this temperature. Once the bottles had cooled to below 60C I put the suspect ones under water and the leaking had stopped so I do suspect that the cap seals soften a bit with heat. I wasn't smart enough to mark the bottles so I won't be able to tell if their carbonation is different to the others unless they have gone quite flat.

Maybe on another occasion it might be worth sacrificing a suspect bottle and letting it cool down in the bath. This will well and truly over-pasteurise it, but should give an idea of at what pressure/temperature the leaking starts/stops. As well as the "quality" of my capping, I imagine that a big variable will be the seal material in the caps which possibly is different for different cap manufacturers... Hmm, always something new to fuss about!

 

[doublejef]

Ok so I'm not the only one having this problem.
This week-end I pastorized a batch of bottle that I let fermented too long, I had a lot of cap poping also a few bottle bomb (even it was big though ones).
I was affrid of loosing also alcool when the cap is leakiig but it's evaporing at 80°C so I don't think there is a risk here.

 

[Maylar]

What do you mean by "that level"? Is there a typical amount that is used at bottling that only functions as an anti-oxidant?

Campden (sulfite) is used at different times for different purposes. At the start of a batch, before pitching yeast, we use it to kill bacteria and wild yeast. At racking and at bottling it's used to inhibit oxidation. As noted above, it can't stop an active fermentation.