# Too much priming sugar... Bottle Bombs?



## whitegoose (23/2/13)

I've just bottle-primed some 500ml bottles thinking they were 640ml bottles - so I've used a slightly heaped 1/2 teaspoon of dextrose, primed and bottled while the beer was about 5-8 degrees. The beer is fermented with US-05, and the bottles are fairly sturdy Weihenstephan bottles.

Do you think that's enough of a mistake to create bottle bombs? I'm terrified of getting glass shards through my face. I usually keg so I'm not really familiar with the maths of carbonation and bottle priming, and don't have any similar experiences to compare to.

Thanks!


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## manticle (23/2/13)

Can you calculate how much (in grams per litre) you have actually put in?

Whether they blow will be a combination of co2 volumes (your sugar + residual co2), strength of vessel and whether fermentation was entirely complete. What was the hottest the batch ever got to, ignoring any short, sharp spikes?


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## whitegoose (23/2/13)

Just realised I gave you the wring details - a slightly heaped half teaspoon of dex is what I prime my 345ml bottles with. For a 640ml bottle I would use a flat teaspoon, so I have actually put a flat teaspoon into my 500ml bottles.

In terms of grams per litre - geez how do I figure that out?

From reading around a bit a flat teaspoon would be approximately 3.2g of dextrose? The bottle is 0.5L so that would make it 6.4g/L?

The fermenter was at about 1 degree when I took it out of the fridge so bottling would have taken place between 5-8 degrees at a guess, so worst case the beer CO2 prior to bottling would have been about 1.45 volumes of CO2?

Does any of that make sense?

Bottles are pretty sturdy and fermentation was complete. What do you think?



In the meantime I've found this calculator: http://www.brewersfriend.com/beer-priming-calculator/ which seems to say that putting 3.2g (1tsp) of dextrose into a 500ml bottle, bottled at about 5 degrees would give me 3 volumes of CO2 - definitely too high, but not bottle bomb territory, right?


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## MaltyHops (23/2/13)

whitegoose said:


> In terms of grams per litre - geez how do I figure that out?
> 
> From reading around a bit a flat teaspoon would be approximately 3.2g of dextrose? The bottle is 0.5L so that would make it 6.4g/L?
> 
> The fermenter was at about 1 degree when I took it out of the fridge so bottling would have taken place between 5-8 degrees at a guess, so worst case the beer CO2 prior to bottling would have been about 1.45 volumes of CO2?


If you have a reasonably precise scale, you could check by measuring out ten flat teaspoons of sugar, weigh it and then divide by 10 to get the weight of one teaspoon. Do this couple of times to get a better average.

Note - the temperature w.r.t. priming is not necessarily the temp of the beer during priming - see _THIS_

Also I have some simple priming charts linked from my sig.


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## Cocko (23/2/13)

Also, maybe throw a good heavy blanket over the bottles incase they do go off!

Can't hurt either way.....


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## whitegoose (23/2/13)

Unfortunately my scales are probably not that accurate. Googling seems to show a generally accepted rule of thumb of 1.25 tsp of dextrose = 4g - which is where I got my "1 flat tsp = 3.2g" estimate.

Assuming that is correct or at least close enough, what do you think about bottle bombs? As I said earlier I bottled at about 5-8 degrees, and after bottling they have generally been quite warm 18-25 degrees on average I would say.


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## whitegoose (23/2/13)

Cocko said:


> Also, maybe throw a good heavy blanket over the bottles incase they do go off!
> 
> Can't hurt either way.....


Yeah I might do anyway, but I'm keeping the faith in that priming calculator that seems to say I'll be okay :unsure:


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## manticle (23/2/13)

Not temp when bottling - highest temp during and after fermentation.
Weigh your 1.5 tsp a few times and average out.


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## whitegoose (23/2/13)

My digital scales only go 1g at a time  They're no good to me.

So, let's just assume that 1 flat tsp = 3.2g of dextrose, and as per my earlier post since bottling they have generally been quite warm, say 18-25 degrees. May have peaked for a few hours closer to 30 degrees in the arvo of that 40 degree day last week while nobody was home and the air con was off. Fermentation ranged between 16 and 19 degrees. EDIT: oh yeah, but then I crash chilled to 1 degree for several days - that was the temp when I took the fermenter out of the fridge for bottling.

I know it's not perfect, I'm just trying to get a rough order of magnitude of how likely bottle bombs are and whether I need to ditch the affected bottles.


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## MaltyHops (23/2/13)

whitegoose said:


> Assuming that is correct or at least close enough, what do you think about bottle bombs? As I said earlier I bottled at about 5-8 degrees, and after bottling they have generally been quite warm 18-25 degrees on average I would say.


Very important is the highest temperature your beer got exposed to during the fermentation stage as it affects how many CO2 volumes you already have in the beer even before priming.

So if we go by your estimate of 6.4g/L, then if your beer got exposed to ~20'C max during most of the fermentation stage, then you're looking at having primed to 2.5 CO2 volumes (using the _One Litre Bulk Priming Rate Chart_ ) You would have to have kept things under 5'C to get close to 3 CO2 volumes.

I think you're most likely to have primed to around 2.5 which is getting towards the danger zone for normal beer bottles, especially if fermentation has not fully finished. A drop of 0.002 SG points gives you one CO2 volume (_BrauKaiser_ - see the part just before FInal Remarks)


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## MaltyHops (23/2/13)

whitegoose said:


> My digital scales only go 1g at a time  They're no good to me.


But if you measure out ten teaspoons, then your scale can weigh that (then divide by 10 to get weight of one tsp)


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## whitegoose (23/2/13)

Right - sorry I didn't get what you (MaltyHops and manticle) were asking me to do earlier - I've just measured my 10 teaspoons of dextrose came to 32 grams, so looks like the web was correct.

I've primed a 500ml bottle with 3.2g of dex.
Primary ferment temp was 17-19 degrees (followed by a -1 - 2 degree crash chill over 3 days)
Bottling temp was about 5 degrees - 8 degrees
Bottle-ferment temp has ranged between 18 and 25 on average.

What do you think? How likely is an explosion? How likely is a gusher?

Thanks again for your help


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## MaltyHops (24/2/13)

Sounds like they'll probably be ok (assuming they fermented out) ...treat with caution, don't give any away, drink them asap.

Did you bottle any of the beer in PET bottles? This is a good way to monitor carb levels.


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## whitegoose (24/2/13)

Sweet, thanks for the input!

Yeah I did bottle some in PET bottles but I primed them correctly. Is that any help?


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## bum (24/2/13)

whitegoose said:


> I've primed a 500ml bottle with 3.2g of dex.
> Primary ferment temp was 17-19 degrees (followed by a -1 - 2 degree crash chill over 3 days)
> Bottling temp was about 5 degrees - 8 degrees


Did you chill as soon as primary was reached or did you wait a while?

If you CCed "immediately" and the temp dropped fast...based on a high temp of 17C (erring towards the cautious side) the calculator I looked at gives you ~2.5 volumes at your assumed priming rate. You should be good to go as long as true FG was reached and your bottles aren't rubbish.


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## whitegoose (24/2/13)

bum said:


> Did you chill as soon as primary was reached or did you wait a while?
> 
> If you CCed "immediately" and the temp dropped fast...based on a high temp of 17C (erring towards the cautious side) the calculator I looked at gives you ~2.5 volumes at your assumed priming rate. You should be good to go as long as true FG was reached and your bottles aren't rubbish.


Hmmmm what if I did wait a while and CC temp was reached over about 16 hours :-/


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## bum (24/2/13)

The longer the temp is at the higher end the more CO2 is going to escape solution. My gut feeling is that dropping over 16 hours isn't going to change the calculator's prediction a lot but the bigger issue is how long it sat after FG was reached (i.e no more CO2 being produced) at a higher temp. The quicker it is the more dangerous it becomes - but, if the assumptions you've stated are all fairly close I reckon you'll just cop a high carb at worst. 2.5ish might sit right where you want whatever style this beer happens to be.

Err on the side of caution, of course. Keep as many cold as you can once they're carbed or in a sturdy box or whatever suits you.


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## whitegoose (24/2/13)

Thanks for the advice everyone


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## MaltyHops (24/2/13)

whitegoose said:


> Sweet, thanks for the input!
> 
> Yeah I did bottle some in PET bottles but I primed them correctly. Is that any help?


Occurred to me that even so, the PET bottles and the bottles in question should condition at similar rates - the b.i.q. ones may just keep going further.

Just keep some PET ones together with the b.i.q. ones so they have the same enviroment. Start drinking the b.i.q. ones as soon as the associated PET ones get firm.


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## manticle (24/2/13)

If 2.5 vol or less calculation is correct and the bottles are not made of the weakest glass ever then you will be fine. Wrap each bottle tightly in glad wrap if you are still concerned.


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## bum (24/2/13)

manticle said:


> If 2.5 vol or less calculation is correct and the bottles are not made of the weakest glass ever then you will be fine. Wrap each bottle tightly in glad wrap if you are still concerned.


The 2.5 vol. calculation is definitely based on some assumptions about highest temp reached vs CO2 in solution so should be taken with a grain of salt. Caution is the word of the day.


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## manticle (24/2/13)

I agree.
I'm a massive fan of caution where glass is concerned.

2.5 is not stupidly high - one could push much higher than that, all else being equal.
Store away from stuff that doesn't like being stained, wrap individually in glad and chill immediately if any go bang is the order of the day I reckon


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