Will my boiling wort crack my 5L demijohn?

[Bats]

I am currently brewing a dark lager.

In the past, I have chilled some of my wort in an erlinmeyer flask to be used as a starter. My yeast starter gets busy for a couple of days whilst my wort chills in the cube (No Chill method).

The Mr Malty calculator has recommended a larger starter than can fit in my erlinmeyer flask due to it being a lager. I am using Wyeast 2000 Budvar Lager yeast.

If I use one of my 5L demijohns, will the boiling wort crack the glass? After I whirlpool, the wort is around 85 degrees when it goes into the cube.

 

[breakbeer]

Should be fine as long as the Demijohn isnn't too cold, sit it in some hot water before filling

 

[manticle]

Wouldn't personally do it but warm it up first with some warm water, then maybe even some hot water to be safe.

 

[spryzie]

I've broken many jam jars trying to make sterile containers of water for yeast, etc.

Glass will break if you pour boiling water into it and it is cold.

I bring to boil slowly, or add boiling water to a hot jar fresh from the dishwasher now.

If it's Pyrex then forget what I just said - it'll be fine.

 

[adryargument]

I blew up a 23L demijohn on the stove trying to make a 10L starter.
I shit you not, it did not crack, it exploded like the 4th of july.

NOT FUN + VERY DANGEROUS!

edit: ^^^^^^^ Stovetop, should be fine from kettle.

 

[manticle]

You had it on an element or burner?

 

[adryargument]

You had it on an element or burner?

Misread sorry, assumed by 'boil' poster was going to chuck it on the stove like i did

 

[Bats]

All good.

I sanitized my demijohn and rinsed it with hot tap water to get the glass nice and hot. The hot wort went in no problems.

The only difference is I am letting it cool naturally so the temp comes down gradually. I reckon putting it in an ice bath will crack it for sure.

At least my wyeast smack pack has time to swell.

 

[Bribie G]

In a previous life I worked in a glassworks and the rule is that with "normal" - as opposed to lab glasses - the thicker the glass is, the more likely it is to crack or even explode when you pour boiling stuff in. That's why glass tea and coffee glasses tend to be fairly thin.

Progressive heating by adding hot then very hot then boiling will step a thick glass container up so that it won't crack.