Same thing happened to me right as I was trying to remove the sealed
bung. Look at a 54L demi-john this way : it has the same thickness as
a 750L bottle, but 70 times the volume !!!!!! So just immagine how
weak it is compared to a bottle. Not to mention the fact that at 30$
CAD, you can not expect to have a Murano glass quality either !

My advice, always put airbung.

(Dan Emerson) wrote in message . com>...
> Well I certainly learned a lesson today.
>
> I had a cabernet all finished sitting in a demijohn, just waiting a
> bit to age and bottle. From last years harvest from Lanza Ranch. I
> had put it in a room with some Sauvignon Blanc that is just finishing
> fermentation, so I was keeping the room cool, about 50 degrees. The
> air lock on the cabernet kept draining into the wine as it changed
> volume due to changing temperature. So I put a bung in it. Good and
> tight.
>
> Today my wife calls me at work to say that there is cabernet all over
> the floor! The demijohn cracked, apparently due to pressure due to
> temperature changes. 54 liters of fine wine all over the carpet. The
> carpet was crap and due to be tossed anyway.
>
> Should a demijohn be able to take the small stresses from temperature
> changes when it is bunged tight? Seems weak to me. Anybody else
> experience this?
>
> I'm bummed.
>
> Dan