Hey all, Noob shitshow here. I had a glass carboy split in half after poring in wort at about 130 degrees and setting it in an ice bath in my kitchen sink (I don't have a wort chiller yet). I've followed this procedure with the same glass carboy for the last three batches with no issue. I am officially switching over to a better bottle plastic carboy, but was curious if you all think there was a fracture in the glass that caused the split--which was then exacerbated by the extreme temperature change, or if extreme temperature changes can simply cause glass to burst?
Yes, extreme temperature changes can cause glass to shatter. To avoid this problem in the future put your kettle in the ice bath instead of your carboy. I don't think I'd want to out 130 degree liquid into plastic..
I would recommend glass, but that’s just a personal preference. I would wait to get it close to pitching temp, rack into the carboy, aerate, and seal that thing up.
Same thing happened to me on my first batch in glass. Glass doesn't like changing temperature fast from hot to cold. Now I chill in the kettle and transfer to glass only when cool. And don't put your glass carboy in an ice bath, not necessary.
So much easier to put sanitized foil over the carboy and let it chill to room temp in ice bath than risk contamination in the kettle tho. I'm thinking keep my current SOP, but switch to plastic (and not transfer from kettle until temp is around 100 degrees).
Maybe I'm misunderstanding you here, but it's not any fun handling hot wort during a transfer. I use a chiller in my kettle and pour the cooled wort into my carboy. I think the wort will also pick up oxygen easier when it's cooled, so that's another benefit of delaying the transfer. Chilling the wort in your kettle is not a high-risk exposure to airborne critters as long as you are doing it in a reasonably clean-air area and not in a garage or barn.
For what it is worth, I have been pouring wort from my stove top right into my plastic buckets for years with now observed ill effects. Granted I do put about one gallon of cold tap water (mine runs around 40-50 degrees F) and some ice blocks in it before hand to help cool it down faster. Then top up with the same tap water and then put the bucket in an ice bath. Never had a carboy, but know temperature changes well enough from the breaking glass side of things.
It doesn't sound very warm, but it's the sudden change that causes problems. More specifically, its the sudden change to part of the glass (the inside) as compared to the rest of it (the outside). The inside tries to expand suddenly, while the outside doesn't. OP said this was the fourth time following this process. Each time, the glass is starting out weaker (more brittle) than the last.
Glass is actually an extremely stable and slow moving non-Newtonian plastic material. Think of it like taffy or silly-putty. When you pull it apart slowly, it will stretch way out without breaking. But if you pull it apart very quickly, it breaks apart. Any sudden stress will break it, including sudden changes in temperature.
Thanks for the physics behind this. All your responses have been helpful in plotting the way forward. At the end of the day, I'm just happy I didn't lose any limbs.
I've never used glass - always better bottles. I chill in the kettle to about pitching temp and then rack over. Never had an infection.
