I was going to point out to barls that cubes probably weren’t designed for boiling wort either but wasn’t sure of my facts so didn’t bother.wide eyed and legless said:I use the cubes for no chill and for cask beer, but I did read just the other day that in America it is advised that any hot liquids being put into the cubes should not exceed 71 degrees C, I initially thought this to be in relation to toxins being leached into the hot liquor from the plastic, but apparently it was referring to getting a safe seal.
Presumably from the pressure of the vacuum as the liquor cools.