Random Exploding Screwtops

[DonMI6]

I have just finished consuming a batch of homebrew made to the following recipie-
1 x Coopers Real Ale
1 x Coopers BE2
1 x LDME
Made up to 22l, brewed at 18c and racked & bulk primed at 7g (Dextrose) per litre.

Bottled into 750ml twist top bottles supplied by various 'associates', they were all fine, except for one bottle which, on the slightest touch on the cap, took off like a champagne cork, barely missing my head & leaving a small dent in the ceiling. The beer was normally carbonated, tasted like beer & kept a decent head.

This was my first attempt at bulk priming having just bought a 2nd fermenter.

Anyone had this happen before & if so, what do you think caused such an apparently random ND.

[gregb]

I've seen that from time to time when pressing commercial bottles into service. My thought is that commercial beer bottles are made to be single use. Often there will be slight flaws in them that will survive the trip out but will blow when a HB is put in.

Cheers,
Greg

[geoffclifton]

I've had what you describe once, I presume the glass did not break. A mate was opening it and as he touched the top it went BANG. There was nothing wrong with the beer.

I you had bottled too early you would expect to lose a few bottles and those you opened may spout foam.

With be2 and 500g ldme you had a fair bit of malt and my guess is you wouldn't be bottling under 10 days. Do you take SG's? As long as your FG was below 1012 and your gear was clean I don't think you have a problem. Just an occaisional surprise

Cheers, Geoff.

[Boonie]

My theory is that it sealed well but it was just hanging in there by the thread of the screwtop. The C02 would be trying to force it off and just the slightest movement may have triggered it.

My only suggestion would be to get the benchcapper as close to the top of the bottle when you cap. I find when I do this it tends to push the cap "around" or clasp the bottle better. When the capper is higher it tends to just "push" it on and not clasp it.

If the glass did not explode, and I have had 0 blow, you are off to a good start

Cheers

Boonie

[Kevnlis]

My theory is that it sealed well but it was just hanging in there by the thread of the screwtop. The C02 would be trying to force it off and just the slightest movement may have triggered it.

My only suggestion would be to get the benchcapper as close to the top of the bottle when you cap. I find when I do this it tends to push the cap "around" or clasp the bottle better. When the capper is higher it tends to just "push" it on and not clasp it.

If the glass did not explode, and I have had 0 blow, you are off to a good start

Cheers

Boonie

I unscrew my bell so that the top of the neck part that moves down is nearly popped out of the slot, I find this gives me a much better space between the top of the bottle with the loose cap and the cap pressed firmly on. The bottles usually stay in the capper and need to be pulled out.

[pacman]

An observation I have made when supplementing my HB by putting down a batch at the local UBru4U. Upon bottling the carbonated finished product, very occasionally a bottle will foam up, and has to be put aside to settle before topping up and capping. The cleaning and sanitising has failed to remove a non infectious molecule sized foreign body. At least, you hope it is non infectious, and so far in my experience no infection has occurred.

Much like pouring sparkling wine into flute glasses. A speck of dust or residue can occasionally result in one flute bubbling away much more vigorously than its peers.

Can the same type of thing occur in HB bottling. No infection, but a higher level of CO2 due to the otherwise harmless speck of foreign material?