Possible Over-Carbonated Plastic PET Bottles.

Hey,

I brewed an Apricot Weizen kit a couple of weeks back. I had it in the primary for exactly 14 days. I usually do 3 to 4 weeks, but I rushed because it's for the wife and I really wanted to get in a stout or something as soon as possible.

I'll try to get to the things I think play a factor in the issue. Let me know if you need the whole build or more info.

Bottled on day 14.
Used 4oz of Brewcraft Apricot Flavor in bottling bucket.
Used 3/4 of corn sugar for priming.
Used 1 liter plastic Mr. Beer PET bottles.

About 24 hours after bottling, the bottles were/are rock hard. It usually takes 1 to 2 weeks for them to get rock hard. I decided to slowly crack one open today to see how much CO2 was in there and it release quite a bit.

I never brewed a Heff before and I'm suspecting that it wasn't done. I don't have a hydrometer yet.

So, I thought about cracking them open to release the CO2. Any thoughts?

Has anyone experienced bottle bombs with plastic PET bottles?

There's definitely krausen around the tops of the bottles. When I slowly cracked it open, sediment was kicked up from the bottom and and floated upwards.

Thanks,
E

What was the batch size? Did the apricot flavoring have any sugars in it? I would vent all the bottles and wait to see if they harden back up again. If so, they are probably still actively fermenting. At that point I'd pour them back to your fermentation vessel, get a hydrometer, and let it finish out.

Eh, maybe go ahead back to the fermenter. Plastic bottles aren't exactly dangerous but can make quite the mess. What's worse? Waiting for beer or painting a room with beer.

Oh. It was a 5gl batch.

Before I bottled, I asked the owner of the LHBS and he said that there were next to none fermentable sugars in it and that I don't need to adjust my priming sugar.


DOH!! Well, I could have put it back in my fermenter...... BUT.... I brewed another batch tonight...

E

Hi!
I had the same problem with a batch of mine. Here's what I made, it turned out good:
- putted the bottles in a solid container, like the bathtub (so you can stop wondering if they explode);
- gently loosen the grip on the cork and let the CO2 come out. Close the bottle again when the beer tends to come out. Doing this 3-4 times a day you should be done in a pair of days.

Cheers from Italy!
Piteko

Gotcha. Thanks for the advice.

I started venting them last night and did it a couple of times today.

I really hope my wife appreciates all this work I'm doing for her..

E

can you find a stopper and airlock that fits in the mouth of the mr beer bottle? You could finish them off right where they are and save yourself the time and worry.

StrikeThree said:

can you find a stopper and airlock that fits in the mouth of the mr beer bottle? You could finish them off right where they are and save yourself the time and worry.

Click to expand...

Well.. I could, but that might get pricey. I have 16 bottles. So far, it's been pretty easy.

I just don't know how many days I need to vent them. It's been 18 days since I pitched the yeast.

E

If I had to guess, I would say PET bottles have very strong capacity for high volume co2 storage. Pepsi and Coke are about 3.7 volumes so I would not worry about any bottle bombs at all unless you say tripled or quadrupled the amount of priming sugar you should have used.

DannPM said:

If I had to guess, I would say PET bottles have very strong capacity for high volume co2 storage. Pepsi and Coke are about 3.7 volumes so I would not worry about any bottle bombs at all unless you say tripled or quadrupled the amount of priming sugar you should have used.

Click to expand...

Correct me if I'm wrong, but:
- 4 OG points are about 1 Plato;
- 1 Plato is 10gr of sugar in 1Kg of worth;
- 10gr of sugar are about 2,5 volumes of CO2.

Starting from 0,88 volumes of CO2 dissolved at 20°C, you can get above 3,7 volumes with (3,7-0,88)/2,5*4= 4,5 OG points left in the fermentation.

All this only to say that yes, PET bottles have very strong capacity, but it's very easy to get high with a non totally fermented worth...

Cheers from Italy!
Piteko

Brown glass bottles can sustain up to 6 volumes of CO2 when new. However, they are usually rated at 4, just like the PET bottles (0.3 volumes are absorbed by the bottle wall, hence 3.7 just like piteko said).

Every product on the market has a "safe range" (expiration, pressure, etc.), but better be safe than sorry.

All that technical stuff went over my head.

I stopped venting them on the 20th. I think they should be good to go now.

Thanks again. I guess that's what happens when you try to rush a beer.

I have a Red Ale in the fermenter now. I can't to bottle that and get a Porter in there.. At this rate, the Porter MIGHT be done by Christmas.

E

One of my PET bottles exploded.. Wasn't bad, the bottom of the bottle split but it was most probably due to a bad bottle. Good thing they're stored in an old esky

Yes, I have experienced bottle bombs with PET bottles. I got this bottle bomb (actually 2) from a recent batch of AHBS's Summer Ale. After 10 days, was at 1.020, put in secondary for another 2 weeks. Bottled in Brown Mr. Beer PET bottles, Coors Light Resealable Pints, 20 oz Gatorade Bottles, and a couple of 12 oz glass bottles. We used the plastic and metal bottles specifically for tailgating as security frowns upon glass bottles.

A couple of weeks after bottling, a beer smell in the beer room led me to a couple of aluminum pints that had blown their lids.

A month after bottling, another odd smell led me to a pair of PET's that had blown their bottoms out. (1 pictured here).

I put what I could in the fridge and the rest in a foam cooler. Another blown aluminum top later (pictured) and I'm out a cooler lid. The screw-on cap was against the closet door, about 5 feet away and bend inwards. Luckily the spilled beer remained in the cooler or on top of the lid, saving my carpet and my marriage.

My guess as to causation is the guy who helped me bottle these wasn't as sterilized as I wanted him to be. Or, the wand didn't leave enough headspace in the PET's. None of the Gatorades have blown, although they are quite puffed up.

I know that without taking an FG on bottling day, I'll never know for sure what went wrong, but the ones we've tasted so far do not taste infected. Likewise, they do not appear hella foamy when poured into a glass. Let's hope it's just a headspace issue.

Bottom line, however, a PET bottle can and will burst under certain conditions, albeit extreme. I share this picture with the group in the interest of science.

Cheers.

Update: to nobody's surprise, the beer that exploded the PET bottles ended up being undrinkable. I did something wrong, probably in numerous steps along the way. Incomplete conversion during mash, lack of sanitation, and probably bottled too early. Ended up fertilizing the palm trees and made some pretty good Beer Pretzels. Kept the rest in the frig to prevent explosions. RDWHAHB #liveandlearn