[Speedslug]

OK First off that 450 from Bulseye is gong to mean centigrade not fahrenheit.

Google says it equals 842 fahrenheit.

Next Boro needs 1000 f I think and 104 coe wants 920 f garaging temperature.

Everything I have seen says figure plus or minus 50 f due to different glass constituents and different kilns and different thermometers.

There is this temp called the "strain point" where what ever stress still in the glass is going to stay in the glass at any temp below that.

For coe 104 I think it is around 820 or some such.

I cool mine at 100 f per hour from garage temp to 800 f.

Under the strain point the internal stress doesn't change but the glass is still susceptible to breaking due to thermal shock so it still needs to cool slowly.

My memory gets sketchy about how slowly to cool from there to room temp but I cool my beads at 200 f degrees per hour down to 400 f then I turn off the kiln heat and just let the kiln cool to 100 f.

Usually this is an over night thing so it is room temp by the time I get up.