PET bottles

[Spursman]

Anyone know how many uses we can get before it's time to replace the bottles? I've got around 90 that are in constant rotation and have noticed a few "soft" ones. I put that down to distorted caps but had one the other day where the cap looked normal.

Bottles are around 2 years old.

[Barramullafella]

I am using new and old PET's. I have used at least 6 times each PET so far with no drama.

[Malter White]

I've been using most of my PET bottles for 3.5 years and they are in constant use. Some are newer. I haven't disposed of any as yet. I dispose of the lid if I get a soft bottle.

Edited June 22, 2021 by MUZZY

[Shamus O'Sean]

You should be able to use the PET bottles dozens of times @Spursman.  Basically keep using them until they do not work any more.  I have been brewing for over 4 years.  Although I keg now, I always do a couple of bottles with the extra volume in the FV.  In that time I have probably thrown 3 PET bottles for not being carbed.

[Classic Brewing Co]

I have about around 150 PET bottles, some of the original Coopers go back 5-6 years but as I have introduced extra FV's I have had to build up stocks of bottles, I have a few boxes of Mangrove Jacks & Morgan's, which are 750ml & also different colour with different colour  tops so it it easy to separate them for different brews - depending which are free at the time.

In an earlier discussion I have stated I have disposed of a few older ones due to the thread other than that, I feel if they are looked after they will last for years.

I also have a large collection of Coopers Longnecks & Grolsch bottles.

As Muzzy states some lids need replacing occasionally. 

[Coopers DIY Beer Team]

We've found that the threads on older bottles can wear to the point where new caps keep cross-threading, rather than screwing down to form a seal. That's probably the time to toss those bottles in the recycling.  

[Classic Brewing Co]

3 minutes ago, Coopers DIY Beer Team said:

We've found that the threads on older bottles can wear to the point where new caps keep cross-threading, rather than screwing down to form a seal. That's probably the time to toss those bottles in the recycling.  

I have found it is only the odd one over a long period, probably because we brew too much, not drink, brew 

[Spursman]

Thanks everyone. Seems like I'll just be replacing tops for a few years.

A related issue - when I get a softie I try to recover it by removing and discarding the top and adding a small amount of sugar then fitting a new cap. Problem is that as soon as the sugar hits the beer it froths up out of the bottle. Anyone got a method that is better?

[Classic Brewing Co]

10 minutes ago, Spursman said:

Thanks everyone. Seems like I'll just be replacing tops for a few years.

A related issue - when I get a softie I try to recover it by removing and discarding the top and adding a small amount of sugar then fitting a new cap. Problem is that as soon as the sugar hits the beer it froths up out of the bottle. Anyone got a method that is better?

I had it happen a few years ago with 6 or so I found  a few gentle shakes & turning the bottles upside down for a few days & then upright for a few, repeat it again if necessary. 

Hope this helps. Cheers.  

[Malter White]

17 minutes ago, Spursman said:

Thanks everyone. Seems like I'll just be replacing tops for a few years.

A related issue - when I get a softie I try to recover it by removing and discarding the top and adding a small amount of sugar then fitting a new cap. Problem is that as soon as the sugar hits the beer it froths up out of the bottle. Anyone got a method that is better?

Get faster at putting the lid on  
I don't have any hands on experience with re-carbonating but I've noticed when bottling beer that has been cold crashed it doesn't foam up as much as room temperature beer.
Are these bottles you've been redoing been cold? It could be worth a try.

[Spursman]

17 minutes ago, MUZZY said:

Get faster at putting the lid on  
I don't have any hands on experience with re-carbonating but I've noticed when bottling beer that has been cold crashed it doesn't foam up as much as room temperature beer.
Are these bottles you've been redoing been cold? It could be worth a try.

Good point, Muzzy, I'll try that out.

Thanks.

[Spursman]

26 minutes ago, CLASSIC said:

I had it happen a few years ago with 6 or so I found  a few gentle shakes & turning the bottles upside down for a few days & then upright for a few, repeat it again if necessary. 

Hope this helps. Cheers.  

Thanks Classic - so this is done with no added sugar, is that correct?.

[Classic Brewing Co]

16 minutes ago, Spursman said:

Thanks Classic - so this is done with no added sugar, is that correct?.

No I didn't add any but the exercise worked fine, they hardened up nicely.

[Tricky Micky]

Okay, I thought I'd post these couple of pics of what has happened to a couple of my Coopers PET 740ml bottles. I want to stress the bottle without the blue elastic band has had several new caps fitted to it and all have done the same thing. The caps were from various batches too.

It's hard to pick up but if you look very closely you'll notice the blue elastic band bottle and its cap have a gap between the ridging of the bottle and the bottom ring of the cap so the cap can be screwed down tight without being impeded. The black under ring of the cap is completely free to spin. 

If you look at the bottle without the blue elastic band you'll notice that the cap tightens down to a point where it squashes the under ring of the cap and is impeded from closing airtight. As I've said this bottle has has several different brand new caps fitted and each one has done the same thing. I can only conclude that the bottle is at fault unless someone can come up with a better conclusion. The bottle failed to carbonate with all the different caps used. I tried caps from different batches as well to no avail. 

It seems the bottle could be at fault not the cap.

[Tricky Micky]

I should have added that the bottles are less than 8 months old and that the thread of the bottle seemed in perfect condition. The caps were not cross - threaded either.

[Classic Brewing Co]

35 minutes ago, Mickep said:

I should have added that the bottles are less than 8 months old and that the thread of the bottle seemed in perfect condition. The caps were not cross - threaded either.

Well for what it's worth I remove the bottom ring when re-bottling which allows you to screw the cap down nice & tight, if it is a brand new cap going on a bottle with the ring already removed that's different. I have never had a problem as the used cap ring on the bottom serves no purpose. 

[Tricky Micky]

1 minute ago, CLASSIC said:

Well for what it's worth I remove the bottom ring when re-bottling which allows you to screw the cap down nice & tight, if it is a brand new cap going on a bottle with the ring already removed that's different. I have never had a problem as the used cap ring on the bottom serves no purpose. 

 I should've added and then added I'd done that as well and the bottle refused to carbonate as well.

Thanks Classic, I think the bottle is ready for recycling. And I'll possibly follow your advice and remove the ring from now on - as you say the under ring of the new cap seems to serve no purpose after you've initially fitted it and used it once.

I think the pic of what's happening here demonstrate that in most cases the under ring of the cap does not touch the upper portion of the cap when screwed down tight. But if you're unaware that this could happen as depicted in the pic then it would be easy to miss this and end up with flat beer I'm guessing.

 

[Classic Brewing Co]

Well as you know when you take a bottle to drink & the cap is new when you twist it, from that moment on you are left with just the cap, the ring has dropped underneath so to get a tight seal on the next bottle I have always removed it. I do understand others will have different opinions, however that is mine.

Cheers. 

[Spursman]

I guess putting a balloon around the neck of re-carbonated suspect bottles will confirm any leaks from that area. If it inflates then it's devo leaking. May be a hairline crack in the bottle or cap.

[iBooz2]

2 hours ago, Mickep said:

It seems the bottle could be at fault not the cap.

You could be on to something there Mick.  I have never had a problem leaving that ring on with any of my bottles so got to wondering if its possible these bottles come out of a different roto-mold (balloon mold , however they make these things) and the neck length is different on some.  All mine are Coopers brand bought at various times, some from Coopers store some from various Dan's.

The measurement my micrometer gives me from the flat of the top to the upper edge of the ring stop flange is exactly 19.8 mm.

One roto-mold could be pumping them out at 19.8 mm and another 18.0 mm.  Or are the tops cut there at the very top by the factory to separate the newly formed bottle from the mold?

I wonder what your faulty bottle one measures?  Academic I know but just wondering.

[thebeerpig]

Here’s a pic I posted awhile ago, on another thread, of the top of one of my bottles that failed to hold pressure. I took it by standing the bottle upside down on my printer’s scanner. The flaw is hard to see without closely inspecting the top of the bottle so it could be worth inspecting the tops of any failed bottles in case they too have similar flaws.

[Classic Brewing Co]

6 minutes ago, thebeerpig said:

Here’s a pic I posted awhile ago, on another thread, of the top of one of my bottles that failed to hold pressure. I took it by standing the bottle upside down on my printer’s scanner. The flaw is hard to see without closely inspecting the top of the bottle so it could be worth inspecting the tops of any failed bottles in case they too have similar flaws.

I am thinking despite the you beaut technology we have there is still the mass production factor, just a tiny flaw & you have a problem. 

[iBooz2]

12 minutes ago, thebeerpig said:

Here’s a pic I posted awhile ago, on another thread, of the top of one of my bottles that failed to hold pressure. I took it by standing the bottle upside down on my printer’s scanner. The flaw is hard to see without closely inspecting the top of the bottle so it could be worth inspecting the tops of any failed bottles in case they too have similar flaws.

Yep I remember that post & pic.  I said at the time most likely caused by using a Stanley knife (box cutter or similar) to split the packaging tape on the top of the cartons.  Very easy to nick the tops of the bottles directly underneath the centre whilst slicing the packaging tape.  Just a guess.

[Malter White]

1 hour ago, iBooz2 said:

You could be on to something there Mick.  I have never had a problem leaving that ring on with any of my bottles so got to wondering if its possible these bottles come out of a different roto-mold (balloon mold , however they make these things) and the neck length is different on some.  All mine are Coopers brand bought at various times, some from Coopers store some from various Dan's.

The measurement my micrometer gives me from the flat of the top to the upper edge of the ring stop flange is exactly 19.8 mm.

One roto-mold could be pumping them out at 19.8 mm and another 18.0 mm.  Or are the tops cut there at the very top by the factory to separate the newly formed bottle from the mold?

I wonder what your faulty bottle one measures?  Academic I know but just wondering.

It crossed my mind also that he got a batch of faulty bottles with shorter threads.

Nice diagram, AL.

[ozdevil]

you all know 

if you guys kegged  

ya wouldn't have to worry about  bottle caps  or soft pet bottles 

or cross threading the threads on pet plastic