Bulk Primed (first) Partial Lager- Overcarbonated?

[Mr.Moonshine]

Howdy folks,
I made up a partial mash bohemian pils which I was planning on handing out at a party, but after a few days it seems entirely too carbonated.
I have an idea as to where I went wrong, but just wanted to get an opinion/check.
I had the beer down between 5-10 degrees in the fridge for a few weeks, did a diacetyl rest at about 16-18 for two days, then put it in to chill back at 5ish degrees before bottling (I don't have a fridgemate, just a fridge with a thermostat which seems to work well enough).
First off, I was in a rush when bottling and when bulk priming, gave it too much of a stir with a sterilised brewing spoon, kicking up alot of yeast into the solution, which seems to be settling out into the bottles fairly well.
Also, I added about 150g white caster sugar (dissolved in about 300ml boiled water) to the fermenter when bulk priming. The beer was still pretty damn cold when I was bottling (10-12c)
I suspect the problem is that the CO2 already dissolved in the beer plus the priming sugar was too much, as the beer was at a stable FG of 1.009 when I bottled.

I was planning to chill them right down and try to vent the excess CO2, but I'm not too sure if it's the way to go. Is there anything else I can do to make sure I don't get a cupboard full of bottle bombs?

Cheers and beers,

Mr.Moonshine

 

[buttersd70]

Chill and vent, as you said. Best option, imo.

As far as temperature and co2 saturation is concerned....the temperature at bottling is irrelevant. The saturation levels for the co2 would have stabalised at the 16-18C temp you did your D rest. Chilling the beer back down after that isn't going to re-introduce co2 into solution, unless it's under pressure, or has a gas source on it. So for the purposes of bulk priming, you would use the D rest temp to work out the saturation. The level of yeast won't effect the carbonation; the amount of fermentables will. The excess yeast only means that it will go through those fermentables faster.

You didn't mention your batch size: based on 16C for the D rest, and assuming a 23L batch size, 150g castor sugar should have given you 2.7 volumes of co2; so if it's overcarbed, either
your batch size is different
your weighing of the prime was off
primary fermentation wasn't as finished as you thought, or
you have an infection of some sort.

 

[Mr.Moonshine]

Chill and vent, as you said. Best option, imo.

As far as temperature and co2 saturation is concerned....the temperature at bottling is irrelevant. The saturation levels for the co2 would have stabalised at the 16-18C temp you did your D rest. Chilling the beer back down after that isn't going to re-introduce co2 into solution, unless it's under pressure, or has a gas source on it. So for the purposes of bulk priming, you would use the D rest temp to work out the saturation. The level of yeast won't effect the carbonation; the amount of fermentables will. The excess yeast only means that it will go through those fermentables faster.

You didn't mention your batch size: based on 16C for the D rest, and assuming a 23L batch size, 150g castor sugar should have given you 2.7 volumes of co2; so if it's overcarbed, either
your batch size is different
your weighing of the prime was off
primary fermentation wasn't as finished as you thought, or
you have an infection of some sort.

Batch size was 20l, which at first lead me to think that 150g was suitable for the bulk prime (based on 8g/ litre which is the normal priming rate for most of my beers). It doesn't taste infected, which would lead me to suspect that it's not. Given that to have gushers in three days it'd have to be a ripper of an infection, I'd have thought some kind of off flavour would be present.
I'm hoping my sanitation of the bottles was up to scratch, I've had infection problems as a result of them before- although this time I cleaned them with bleach/vinegar no rise solution, then risned with tap water, then baked in an oven with foil wrapping over the top @ 150 degrees for about 3 hours. Admittedly I did do the baking a few days before I bottled, but I'd read around that if the foil on top is intact then they remain sterile/sanitsed until the foil seal is removed.

 

[Mr.Moonshine]

I tried to vent the beers by uncapping and recapping, some went very easily, but most started gushing pretty soon and either ended up mostly in the sink or all over the bench.
I figure I must have overcarbed it somehow, as the ones that gushed the fastest also had the most yeast in them (Which would make sense, given Butters point). I've got them chilling down in the fridge again, might have to vent again, or else just drink them all with mates this friday.
Assuming no infection, I guess the measuring scale was off a fair bit >< I'll have to fix that up quick smart. Seemed a bit odd that it'd get overcarbed so fast given that I used the same amount I'd use for a similar ale.

 

[Hefty]

at 5ish degrees before bottling
when bulk priming, gave it too much of a stir with a sterilised brewing spoon
The beer was still pretty damn cold when I was bottling (10-12c)

Forgive the choppy quoting.
In the past I've had some beers that I've bulk primed when cold end up with really uneven carbonation between bottles. A few way over (once it caused some bottle bombs), some about right and several way under.
Don't get me wrong, I'm all for bulk priming and most times I've never had trouble with it, but I'm starting to wonder if priming sugar (even pre-dissolved) in cold beer struggles to distribute evenly. If it was not pre-dissolved I can see how stirring it in would almost whirlpool it which could lead to excess sugar in some and less left for the rest.
With pre-dissolved sugar I'm wondering if the rapid change in temp might cause the sugar to re-crystalise and end up whirlpooling in the same way.
Maybe uneven stirring patterns could help this?

As you can see by the number of times I've said "I wonder", this is entirely specualtion but it could possibly help to explain the situation. Can anyone who is more "in the know" confirm or refute this?

HABAHAGD!
Jono.

 

[FrankieV]

The only time I had trouble was when I didn't dissolve the sugar.
Now I slowly poor the dissolved sugar in a circular motion to spread it around.
For the stirring, I put the spoon in at the deepest I want it to go and then grab the spoon so my arm touches the top of the tub. The yeast cake stays nice and settled while stirring.

 

[Nick JD]

Forgive the choppy quoting.
In the past I've had some beers that I've bulk primed when cold end up with really uneven carbonation between bottles. A few way over (once it caused some bottle bombs), some about right and several way under.
Don't get me wrong, I'm all for bulk priming and most times I've never had trouble with it, but I'm starting to wonder if priming sugar (even pre-dissolved) in cold beer struggles to distribute evenly. If it was not pre-dissolved I can see how stirring it in would almost whirlpool it which could lead to excess sugar in some and less left for the rest.
With pre-dissolved sugar I'm wondering if the rapid change in temp might cause the sugar to re-crystalise and end up whirlpooling in the same way.
Maybe uneven stirring patterns could help this?

As you can see by the number of times I've said "I wonder", this is entirely specualtion but it could possibly help to explain the situation. Can anyone who is more "in the know" confirm or refute this?

HABAHAGD!
Jono.

Do a little experiment - stir in your bulk prime sugar as you normally would and then take samples from the wort at various places with a turkey baster or similar and measure the SG.

I don't bulk prime because I've never been able to get the sugar adequately distributed without introducing a lot of oxygen. Mixing two liquids, one at 1.100 and one at 1.010 needs a lot more stiring than many people think.

 

[manticle]

I would hazard a guess (as butters has suggested) that fermentation wasn't finished when you bottled.

As an aside, I've heard baking bottles will weaken the glass.