Oven-sterilised Bottles

[deebee]

This will be no news to some, but I have discovered oven-sterilising for bottles. My oven fits 28 long necks and 6 stubbies when full. Make sure they are clean. Wrap a bit of foil over the top. Pack em in the oven and cook em. There's a table in palmer's book giving times and temps.

The beauty is that you can do the job whenever you have a bit of spare time then store the bottles afterwards and they stay sterile (not just sanitised) with the foil on top until you need them.

Bottling is then a simple expercise of rack to bulk prime, bottle and cap. No sanitising. It has made my bottling days heaps easier especially since I am trying to do three brews at a time to catch up after depleting stocks over summer.

 

[Murray]

I do this as well. If you want to be pedantic, get a high-temperature thermometer and calibrate your oven. Mine is approximately 10C lower than what the dial says.

 

[PostModern]

You should ramp the temp up gradually over a few hours to avoid thermal shock weakening the glass. I wouldn't be prepared to risk my 1970's tallies with this process.

 

[deebee]

Could they not crack but still be weakened?

I just follow Palmer's recommendation of 5F per minute and take them up in steps over about 40 minutes then let them cool in the oven.

 

[joecast]

this is also a good way to get rid of any pet bottles you dont need anymore.

sorry, couldnt help myself.
joe

 

[Linz]

Joe,

wouldn't they turn out like shrinkey dinks????? a poofteenth of their original size. Bottle 20ml at a time


RALMFAO

 

[PostModern]

Could they not crack but still be weakened?

If you ramp the temps properly, there shouldn't be a problem... shouldn't be.

I used to work for a glass company. Down in the factory they had a glass toughening machine (it makes toughened safety glass such as that used in sliding doors, shower screens etc). Basically how it works is to get plain "float" glass (cut to size and edges polished) heat it up under extreme pressure then let it cool gradually. What happens is that the crystals in the glass change alignment and instead of breaking on cleavage planes like untreated float, the toughened glass will shatter into tiny pieces.

Of course the machine operates at temperatures you couldn't dream of achieving in your oven and at very high pressure that you also cannot achieve at home, and float glass is dissimilar to bottle glass... etc etc etc etc, but I still believe that the nature of the glass will change after a heat treatment like that. Ever dropped a stubby in the camp fire? Once it cools, the molten mass is much more brittle than the original bottle.

I'm not aware at what temps the crystals change nature, etc. Just raising a small red flag Kept at not much over 100C, it should be fine.

What temps does Palmer recommend?

EDIT: I also edited the title of this thread. It said "Over sterilised" which made me scratch my head for a while. How can a bottle be "too sterile"?

 

[Justin]

I used to sterilise my bottles this way, with a cap of foil over the top. Will keep indefinetely. Never had a broken bottle in my experience. I think the important part, as outlined by deebee, is to let them cool slowly in the oven. I use the 170oC for 60min.

Lately I've been slack and haven't been sterilizing my bottles in the oven, just using iodophor. What a pain in the ass! I've kegged the last two brews and bottled the left over which is only 2-3 bottles I've now worked out. I'm going back to oven sterilizing from now on so that I can just have a stock of sterilized bottles and grab as many as needed with out piss farting around sterilizing a couple of bottles with iodophor because I'm always dead lazy with these few bottles, I'm bound to get an infection in them.

I like the oven sterilizing technique and I'm going back to it, the only annoying thing is my new house only has a small over. My 2c worth.

JD

 

[deebee]

PM thanks for editing the title.

I was just too lasy

 

[PostModern]

No worries. That's what they pay me for