# PET vs glass.



## [email protected] (17/2/16)

My most recent batch I used some PET bottles for the first time along with glass bottles. Today I drank a PET followed by a glass. The PET was basically flat but the one from glass was like this. 





I batch prime, so the only variables are the volumes of the bottle 500ml vs 750ml and the material. What's the story?


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## Cervantes (17/2/16)

I experienced the same with beer that I'd carbonated in the Keg and then transferred to PET bottles. The PET bottles just didn't seem to retain the carbonation.

Now if I bottle beer at all I use glass bottles and have given the PET bottles away.


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## Smokomark (17/2/16)

Slawson said:


> My most recent batch I used some PET bottles for the first time along with glass bottles. Today I drank a PET followed by a glass. The PET was basically flat but the one from glass was like this.
> 
> 
> 
> ...


Do you use new lids every time on the pet bottles? 
Is the headspace the same, this does affect carbonation levels


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## ianh (18/2/16)

Were the PET bottles the Coopers brown bottles, soft drink bottles or juice/water bottles. You should have no problems with the first two providing the headspace is ok and they are kept at 20C or so for a few days.Whilst I keg I do 2 by 1.5L PET bottles per batch and have no problems with carbonation for the first year. I also reuse the caps.


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## Yob (18/2/16)

You have simply done something wrong, not tightened enough is my guess.

I've seen truck loads of highly carbed pet (the brown ones) at comps, swaps and my own.

If carbonation is low, there is a limited amount of reasons why. 

Not enough sugar
Not enough time
Temperature 
Seal

Not beyond all realms of possibilities that at a long stretch, it's a bad batch.

You can always take the lids off and Re prime too.

500ml? 

W can almost rile out the first 3 due to your info so I'm sticking with seal.


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## Rocker1986 (18/2/16)

I wouldn't have thought small headspace differences would make that much of a noticeable difference in the carbonation in that one is properly carbed and another one is flat. My bottles all have different levels albeit not massively different, but different, and they all have basically the same level of carbonation in them.

I'm also guessing lid seal on the PETs.


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## [email protected] (18/2/16)

They were brand new brown PET made for beer, not coopers but I forget the brand. This was my first time using PET. I've popped another in the fridge to try out. Hopefully it was just the one bottle with a loose lid!


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## kaiserben (19/2/16)

My PETs and glass bottles carb up exactly the same.

I usually use a combination of PET and glass for each batch. 

Very rarely I've had a PET bottle completely flat, which I had to assume was due to an onstruction in around the lid/seal (it's happened to 2 bottles out of about 500).


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## [email protected] (21/2/16)

So I've drank my way through a couple of the PET's now, as well as a few more swing top glass as well, all the PET's are well under carbed compared to glass. So I guess the lesson is tighten the lids REALLY hard. 

Could it be worth opening up the remainder and dropping a touch of sugar into each of them then sealing em up again?


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## Feldon (21/2/16)

Slawson said:


> They were brand new brown PET made for beer, not coopers but I forget the brand. This was my first time using PET. I've popped another in the fridge to try out. Hopefully it was just the one bottle with a loose lid!


Did you tighten the caps down all the way.

On first use you have to screw the caps down hard to get the tamper-proof ring to engage and lock onto the neck of the bottle.

Then, when you unscrew the cap the ring is snapped off the underside of the cap and is left behind on the neck of the bottle.

Have you done it this way?


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## [email protected] (21/2/16)

Yes, they were definitely tightened past the tamper-proof ring! I thought I'd given them a pretty good twist to tighten up, the bottles do feel firm before going in the fridge, like there's pressure inside. After they've chilled down they're a little softer, I assume as whatever pressurised gas is left in the headspace has dissolve back into the beer with the lower temps.


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## motman (21/2/16)

I have had variable carbonation batch priming when I assumed the process of transferring beer on top of the bottling sugar (dissolved in half a litre or so of boiling water) would mix it well enough.. Wrong! The early bottled beers were higher carbed. Problem fixed when I started giving it a good stir.


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## ianh (22/2/16)

Slawson said:


> Yes, they were definitely tightened past the tamper-proof ring! I thought I'd given them a pretty good twist to tighten up, the bottles do feel firm before going in the fridge, like there's pressure inside. After they've chilled down they're a little softer, I assume as whatever pressurised gas is left in the headspace has dissolve back into the beer with the lower temps.


First thing I used to do when using the brown PET bottles was to get rid of the tamper-proof ring and just use the cap. An advantage of PET bottles is you can squeeze them to see how well carbed they are.


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## [email protected] (22/2/16)

motman said:


> I have had variable carbonation batch priming when I assumed the process of transferring beer on top of the bottling sugar (dissolved in half a litre or so of boiling water) would mix it well enough.. Wrong! The early bottled beers were higher carbed. Problem fixed when I started giving it a good stir.


That's interesting that the PET's were the first I bottled. I guess that means I can eliminate thoroughly mixing of the sugar as the problem in my case.


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## Cardini (30/3/16)

Hi All,

This is my first post here,. I am a Noob having bottled my first beer in PET bottles about 6 months ago. Really starting to enjoy it.
this thread has been an interesting read as I too am experiencing inconsistency with the head retention and carbonation on my recent Brews.
I am now using both Brown PET and re-using 1.25 soft drink bottles. I am bitterly (pardon the pun) disappointed at the lack of carbonation in both types of bottles. In my most recent batch
the Head on the beer started well, but ended up more like the head on a soft drink, quickly participating.

All of the bottles feel as tight as a drum so I doubt they are not holding pressure.

I approached the two Brew Shops close to me and they gave me a range of symptoms - from lack of conditioning time (I usually leave the bottles to condition for four weeks) to the wetting agent in the detergent I use on my glasses, to the fact that plastic bottles will leech and finally the type of glass the beer is presented in. All of these answers make sense in their own way, however the lack of carbonation in the beer is absolute let down particularly after such a long wait.

my questions are.
what is the experience of the more seasoned Brewer? is there a way of checking to see the carbonation process has fully completed?
what on average is the useful life of the bottle tops for PET?
What is the useful life of the PET bottles themselves?

thank you in advance,
From a Frustrated Noob.


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## Yob (30/3/16)

Sounds like you have a decent home brew store... All of those points he raised could well be valid.

What recipe?

PET bottles are good for years.

Start with the glassware, rinse thoroughly, drain and eliminate that from the equation.

4 weeks is not long to condition but I know how hard it is to leave them alone. I'm tipping it's a conditioning time thing, better at 6 weeks, much better at 12.. Who has the time though right? Leave one or two bottles to try at those ages to compare. 

Sounds like they are carbed if the bottles are tight so play with the other variables first.


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## burrster (30/3/16)

Cardini said:


> Hi All,
> 
> This is my first post here,. I am a Noob having bottled my first beer in PET bottles about 6 months ago. Really starting to enjoy it.
> this thread has been an interesting read as I too am experiencing inconsistency with the head retention and carbonation on my recent Brews.
> ...


I have PET bottles 3 years old with most of them having the original tops, all with no issues; so bottle/ cap life, 3 years and counting. I don't notice a difference between my glass and plastic, aside from a slightly differing taste, buts that's OT. 
What is your recipe? How do you prime your bottles? What temperature are you conditioning your bottles at?(if it's too cold it just may not be ready yet)
I've found most of my kit brews struggled to hold a head. I now brew all extract brews with added grain and hops, and have no issues with head retention. I also find 4 weeks conditioning is border line for decent head retention. 5 to 6 is better. 
Either way I'm confident it's not the bottles.


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## klangers (30/3/16)

I've had negative experiences with PET.

Pros:

Cheap
Light
Don't explode into shards
Can easily tell if carbonation has occurred by observing "tightness" or rigidity of the bottle
Cons:

Have significantly more oxygen permeation than glass or cans (so no good for aging generally)
Depending on original quality, not as durable
In my experience, the base of the petaloid bottom (where the injection mould originates) can crack such that it does not leak at atmospheric pressure, but the cracks actually open up under carbonation pressure and discharge just enough volume to leave you with a low-filled, flat bottle


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## Grott (30/3/16)

Yob said:


> Start with the glassware, rinse thoroughly, drain and eliminate that from the equation.


Spot on, first thing you must eliminate otherwise you could be chasing ghosts. Make sure there is no detergent film in the glass, suggest you clean in very hot water using a "brand new" cleaning cloth. Also remember in testing head retention make sure your not eating at the time as oils etc from the lips can flatten any head (beer) in no time.
Cheers and let us know how it all goes.


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## Cardini (30/3/16)

Thank you all for the input.

I think it might simply be my impatience to tuck into the brew :icon_drool2:. I might give it another couple of weeks and see how things go.

I should add that I have been cleaning the fermenter, the bottles and their tops in water and a bit of bleach. I wonder if this might have some effect. that said, thoroughly rinse with clean cold water. 

my recipes have been very simple, mostly Pale Ale (Coopers) and 1kg light dry malt. Just getting into dry hopping. I wanted to try them individually so I can identify them in the brew. just giving Mosaic a try in the current brew. then I can better understand what to use when trying to match the commercial beers I once sought out at the bottle shop.

thank you all again. I look forward to getting more involved in this site.


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## Bribie G (30/3/16)

Bottles made specially for beer have a layer of a related plastic sandwiched in, that reduces oxygen permeability. I've never had problems with the brown beer style bottles.
Before I went to kegging I used soft drink 2L and 1.25L bottles that made good little Mini-kegs but I wouldn't use them for long term storage or maturation.

This year I've decided to go all-glass for my competition entries as some of them will be matured for up to 3 months. This means having to buy and drink a fair amount of Coopers Sparkling. Oh the humanity.


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## jayjt29 (31/3/16)

I know its been said before, but I've had no issues with carbonation in PET, must be the seals or under primed, or as you say to eager to drink them 

Cheers
Jay


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## Yob (31/3/16)

Bribie G said:


> This year I've decided to go all-glass for my competition entries as some of them will be matured for up to 3 months. This means having to buy and drink a fair amount of Coopers Sparkling. Oh the humanity.


Commiserations

I've recently gone the other direction, even gave my capper away. It's either growler / keg for home use or PET for comp entries.


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## decr (14/4/16)

A bit late into the conversation but I've never had any issues carbing up in PET. I use 1.25-2l soft drink bottles for all my brews, hell the cider comes out overcarbonated (priming with juice, my fault etc), pouring that into a pint you get half cider half froth at worst.

I'm not too sure about conditioning or storing brews in the plastic, mine seem to disappear before I get to that point...


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## Grainer (14/4/16)

Ask Yob.. he's an expert on this


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