I am wondering if anyone washes yeast with this method...

[SemperFermentis]

Mason jars and lids are not designed to hold pressure. Under pressure the lid will lift enough to release pressure, unless the ring is tightened to the point that doesn't allow the lid to lift until a dangerously high pressure is reached. This could explain why only one exploded.

Could this be the reason? Possibly, and I can tell you for sure that it was not the Star san.

I assumed this to be exactly the reason, however if you're talking about sealing yeast inside one of these jars with recently boiled water (read minimal, if any oxygen) and having finished fermenting, I don't understand where the pressure would come from...unless fermentation continued somehow. Although now that I think of it, contamination could have contributed to fermentation. Interesting that this would have taken place at refrigerator temps.

The only logical explanation is that it came from CO2 production, which I had assumed (incorrectly) was attributed to the Star San. Now the only logical thing that I can draw as a conclusion is that the wort was somehow not finished fermenting, however I find that confusing as my process has not changed outside of the Star San change. If there's another reason, it's lost on me, and there are no other alternative explanations to be found throughout this discussion.

I've been doing this for two years now, and I've never had a problem before, or since this incident. Using Star San would definitely make my life easier, so I'm glad to know that this is wrong, but I would like to know conclusively.

 

[bja]

The only logical explanation is that it came from CO2 production, which I had assumed (incorrectly) was attributed to the Star San. Now the only logical thing that I can draw as a conclusion is that the wort was somehow not finished fermenting, however I find that confusing as my process has not changed outside of the Star San change. If there's another reason, it's lost on me, and there are no other alternative explanations to be found throughout this discussion.

I completely agree that CO2 was produced from incomplete fermentation. I often open a jar and release slight pressure. I was only giving a possible explanation why only one exploded. Starsan can be slippery. If the jar and ring was still wet, it would've been very easy to over tighten the lid.

 

[bzwyatt]

Did the warm up a lot? Temp=pressure

 

[SemperFermentis]

Did the warm up a lot? Temp=pressure

No, it went from room temperature to the refrigerator. Two days later:

*BOOM*

At this point the only two options I think I cannot rule out was either the fermentation wasn't finished, which would surprise me, or that it caught something in the ambient air that allowed it to ferment further than the yeast would have otherwise.