Oven Bottle Sanitation

[abraxas]

Has anybody here had any experience with oven sanitation of beer bottles.

I have read about it in Palmer's book and think I might give it a try fo my next batch. The thing that concerns me is that I have read mention somewhere on the internet that this might weaken the glass. Is this in fact true? Is there the potential for undetectable thermal stresses to exist after heating glass to 350 for an hour or so?

I guess I'll have to give it a try...

 

[budbo]

Is there the potential for undetectable thermal stresses to exist after heating glass to 350 for an hour or so?

Absolutely! Pouring near boling wort (200ish degrees)in a glass carboy can cause it to weaken it enough for the bottom to separate. There is a very good reason that Glass cookware (and glass lids especially) are specifically marked as "Oven safe"
I doubt doing this one or 2 times is going to ruin your bottles (unless they are thin ones) but if you do it regularly it is inevitable that they will start cracking as they cool.... Why you would do this I don't know, if you fast cool them they are likely to crack, considering the amount of sanitizer needed to do a batch of bottles is cheaper than the gas or electricity you need, not to mention the extra time involved, Sanitizing in the oven it doesn't really make sense.

 

[Sumta]

I had never heard of anyone doing this of purpose. Back just after college my roommate stuck some plates and glassware in the oven thinking it was a dishwasher. He came to his senses later that night, and wanting his frozen pizza, preheated the over to 400...

 

[Ivan Lendl]

yeah thats kind of overkill, your talking sterilization with dry heat, all you need is sanitation, which can be as easy as washing and rinsing, to using a no-rinse sanitizer.

 

[abraxas]

Absolutely! Pouring near boling wort (200ish degrees)in a glass carboy can cause it to weaken it enough for the bottom to separate.

This has more to do with the local temperature variance and inability of the the glass to deform to match the thermal deformation. If you heat slowly enough (or with a high enough air velocity) to ensure uniform heating you can heat the glass up to a much higher temperature than 200 degrees.

I doubt doing this one or 2 times is going to ruin your bottles (unless they are thin ones) but if you do it regularly it is inevitable that they will start cracking as they cool....

So you are saying that heating and cooling does cause some residual thermal stresses which will become more more pronounced the more times I do this?

 

[brewhead]

star san - it's cheap - easy and it works. 4 out of 5 homebrewers recommend star san

 

[abraxas]

I had never heard of anyone doing this of purpose. Back just after college my roommate stuck some plates and glassware in the oven thinking it was a dishwasher. He came to his senses later that night, and wanting his frozen pizza, preheated the over to 400...

My friends had a party one night at which the counter near the oven ran out of spots for emptys prompting people to fill the oven with the bottles, which the host unfortunately did not notice till she had preheated the oven the next day, bottles labesl and everything. Luckily nothing broke nor started on fire.

 

[abraxas]

considering the amount of sanitizer needed to do a batch of bottles is cheaper than the gas or electricity you need, not to mention the extra time involved, Sanitizing in the oven it doesn't really make sense.

I work in an R&D lab for an oven company. I run an empty oven all the time in order to test various things. It would only cost me the foil caps to bring the bottles in and throw them in the oven while I was testing something else, then I would have ready to go bottles anytime without the need to include chemicals (no mater how benign).

I am just concerned with residual stresses in the glass.

 

[Lou]

i've used the oven to sanitize my bottles for several batches. it works very well and saves me the hassle of having to splash sanitizer all over the place. however, i stopped doing this because i decided the risk is not worth the reward. i am absolutely certain that thermal cycling will weaken the structure of the glass, but i can't be sure of how significant this weakening is, how many times it wi be able to handle the cycling before failure or at which stage of the process the bottles will fail (another cooking cycle, capping, or simply containing a highly carbonated wheat beer). all of these uncertainties were making it hard for me to complete the RDW part of RDWHAHB....

 

[Pimp Juice]

Been doing it since the begining.
I always wash my bottles right after finishing a beer.
First I do a quick dust rinse, then set the oven to warm (180 on my oven), leave them in for about 15 mins. The residual moisture from rinsing them steams off and they come out dry and sterile.
Bottles are a little different from the carboys, since they are heat tempered. I don't think 180 is going to effect the bottles.

I have heard of some folks doing a rinse without sanitizing. The alcohol and the hops kind of preserve the beer.

 

[bikebryan]

Been doing it since the begining.
I always wash my bottles right after finishing a beer.
First I do a quick dust rinse, then set the oven to warm (180 on my oven), leave them in for about 15 mins. The residual moisture from rinsing them steams off and they come out dry and sterile.
Bottles are a little different from the carboys, since they are heat tempered. I don't think 180 is going to effect the bottles.

I have heard of some folks doing a rinse without sanitizing. The alcohol and the hops kind of preserve the beer.

Putting them in the oven at 180 degrees won't steam clean them - it certainly won't get them anywhere near sterile. Commercial autoclaves need to use pressurized steam, held at pressure for several minutes, to sterilize, and you oven at 180 degrees doesn't come anywhere near those temps.

Does it "sanitize?" We could debate about that until the cows come home. I wouldn't trust it, but if it works for you, so be it.

 

[Beer Snob]

You know this just seems like a hell of a lot of work. Then everything is real hot on top of that. If you use a liquid sanitizer your ready to go in minutes.

 

[budbo]

This has more to do with the local temperature variance and inability of the the glass to deform to match the thermal deformation. If you heat slowly enough (or with a high enough air velocity) to ensure uniform heating you can heat the glass up to a much higher temperature than 200 degrees.?

In a controlled environment yes, throwing bottles into a hot oven no. Why would you even bother, heating the bottles for 20 min then cooking them for an hour, then slowly cooling them for an hour to prevent damage when you can sanitize them with the same effect in 60 seconds, for about a dime.

So you are saying that heating and cooling does cause some residual thermal stresses which will become more more pronounced the more times I do this?

Basic physics, stressing the glass like that weakens it every time. Same principle as metal, only it happens much faster in glass. At home you are not going to ever deal with the temps needed to stress metals like that but glass doesn't take much more than a couple hundred degrees to weaken, and yes it is cumulative.. Your Corningware is eventually going to crack from the stress of cooking with it, it is made so that it will last long enough you aren't going to care when your 5-10 year old casserole cracks from heat stress.. bottles are not designed that way. They are designed to be used then melted down and recycled. They are not made to sterilized multiple times.

I am just concerned with residual stresses in the glass.

Then just say no. Anything made with heat is going to weaken by applying temp fluxes. The Military routinely xrays Aircraft to check for stresses on the metals, one they look at is friction heat stress.

I learned my methods here.. If I buy them, I clean with soap then rinse and put away.. Commercial bottles soak in oxy-clean to remove labels and clean.. then store.. Homebrew bottles get rinsed in warm water then put on the bottle tree... all get a shot of starsan or idophore before re-filling takes me 15 min to sanitize enough for 5 gallons. Shoot sanitizer in, drain back in the shooter thingy and put on tree.. the beauty is even if they arent completely dry just fill em and they fine.

 

[parasonic]

So you are saying that heating and cooling does cause some residual thermal stresses which will become more more pronounced the more times I do this?

Unlikely. I don't have a degree in Material Science, but the glass is never heated to a high enough temperature to cause enough crystalline deformation, nor is it heated and cooled quickly enough to change the crystal structure to "weaken" it. Possibly if you did it enough over long enough time. If it is, your glass will break due to inevitably uneven cooling. Remember that this stuff tends to expand as it's heated and contracts when it's cooled. Too much internal stress, like, from twenty degrees of temperature difference, will cause the glass to warp, and since it's amorphous anyway, it's REALLY going to want to crack.

You can only drop a hot Erlenmeyer flask in cold water when it's borosilicate, and it's very chemically different from "ordinary" glass.

 

[magno]

I agree with budbo on this...

Eventually those bottles will break, and you dont know when that will be (my guess would be under carbonation in your closet). The benefits come very far from outweighing the potential, and inevitable consequenses. Sanitizing is quick, easy and cheap when you use Iodophor (or Star-San), especially with a bottling tree.

- magno

 

[abraxas]

Basic physics, stressing the glass like that weakens it every time. Same principle as metal, only it happens much faster in glass. At home you are not going to ever deal with the temps needed to stress metals like that but glass doesn't take much more than a couple hundred degrees to weaken, and yes it is cumulative.. Your Corningware is eventually going to crack from the stress of cooking with it, it is made so that it will last long enough you aren't going to care when your 5-10 year old casserole cracks from heat stress.. bottles are not designed that way. They are designed to be used then melted down and recycled. They are not made to sterilized multiple times.

Heating can greatly improve the characteristics of steels, depending on cooling rate and subsequent microstructures formed. Glass (soda lime) has an entirely different microstructure

can you back this up with some personal experience (n=1) or a source? Intuitively it seems that because heating could never be completely uniform, variations of temperature might result in microfractures/streses or something similar that might weaken that glass over time. I have talked with some people however who haved heated bottled for years without a single problem, though I can't say I recall the temperature or the length of time

Seems more likely that scratches from use are at least as likely the culprit here.

 

[chillHayze]

You seem to be set on cooking the bottles, so just do it. Try 300F for an hour with a slow cool.
We are kicking a dead horse here.

 

[budbo]

Heating can greatly improve the characteristics of steels, depending on cooling rate and subsequent microstructures formed. Glass (soda lime) has an entirely different microstructure

Absolutely true, Tempering steel is heating it to red hot, then flash cooling it (makes it stronger). However, once it is tempered, if you do it again, it will shatter.

If you want to heat the bottles go for it, but if you are sterilizing them each time you heat them you are weakening the molecular bonds..

 

[Schlenkerla]

Glass can not be tempered, it is strengthened by thickness. ..

I'm an engineer for a window company. Glass is temperable. Safety Glass is Tempered. By code, every large window/door over 5' is usually tempered. The most common every day glass is annealed.

You can tell by how it breaks. 3-4 shards is annealed, 10 million tiny pieces is tempered. Cars have tempered glass.... ...So you don't get de-capped in an accident.

Bottles are annealed. Tempering glass is a long process of gradual heating at temps much higher than an ordinary oven. If you heat the bottles you would be incrementally making them tempered. Very prone to breakage, much safer if you over carbonate.....:cross:

I would never consider heating bottles for brewing. Its too much of a hassle. Maybe if I was trying to culture yeast that required sterile condtions, I might do that.

I always use One-Step. Its easy, safe and no rinsing.

http://www.ecologiccleansers.com/whyOS.html

 

[budbo]

I Thought tempered safety glass was made differently