Originally Posted by CypherEnigma
Mmhmm! Seriously, when you consider the temperatures that glass is worked at, even 150 degrees isn't going to be enough to crack a well annealed and blown glass vase. But given the quantities that these products are made in to meet the demand, the quality plummets and what you're left with is this. Glass doesn't anneal properly or any one of the other plethora of problems that come with the mass production of this scale and you're left with a cracked base. My condolences and I hope your next base isn't as defective.
150 might actually, we dont crack our annealers until they are under 200*f and the shop is usually between 80*f-120*f so there is not a huge shock, and even then we usually dont open it all the way until its in the lower 100s.
when glass is worked you always keep it above the stress point (depending on the glass it is between the upper 700s and upper 800s for a soda lime furnace glass) and as long as the piece is kept above the annealing temp (910-960 depending on the exact soda lime furnace glass) you will have a hard time shocking it enough to crack it and only be able to crack it if it is relatively cold (below 1000-1200) just by thermal shock (physical shock with a bit of chilling will allow you to break things easily