Disclosure: Long post – buckle up. I’ve tried to do this all accurately with references – I could have easily made a mistake.
Searching for annealing schedules from what I would deem trusted sources produces a wide variety of key temperatures, ramp times, hold times, and overall cycle times.

I understand that there are many ways to achieve the same goal with annealing. Also different kilns and different shape glass structures may require special cycles. However, I believe it would be of great benefit to the community to produce an accurate general table of annealing schedules / annealing cycles for borosilicate glass ranging in thickness from 1mm up to 152mm thick.

What surprises me, is how dramatically different the information about annealing is from one source to another.
This leads to the questions of: Is there an accurate set of formulas for calculations? Which source should be used as a trusted guide for annealing? How can we get semi-accurate schedules for a given thickness of borosilicate?

It is hard for me to find multiple sources for annealing information about thicknesses of borosilicate greater than 0.5 inch (12.7mm) so I will use that dimension as the comparison thickness from each source. Below are general kiln annealing cycles which range from 12mm to 12.7mm thickness.

Northstar for 0.5” (12.7mm) thick boro:

Source: http://northstarglass.com/users-manual/annealing/

1050F (566C) for 2 hours
925F (496C) for 1.7 hours
850F (454C) for 0.5 hours
700F (371C) for 0.5 hours
500F (260C) for 0.3 hours
Crash
Total Hours: 5 hours (300 minutes)

No ramp times listed. No times for initial heating. Northstar provides calculations to determine hold times, but unfortunately the formula doesn’t reflect accurately into the chart of times they provide.
(Example: the above 925F hold should be for 2 hours and the 500F should be for 0.5 hours according to their formula.)
The times depart greatly from their formula the greater the thickness of the glass.

Simax 12mm thick boro:

Source: http://www.simax.com/en/section/32-simax-glass-mass.html
(towards bottom of page)

Ramp from 20C to 550C at 8C per min (66.25 minutes)
Ramp from 550C to 560C ?
Hold at 560C (30 minutes)
Ramp from 560C to 490C at 0.6C per min (116.67 minutes)
Ramp from 490C to 440C at 1.6C per min (31.25 minutes)
Ramp from 440C to 40C at 8C per min (50 minutes)
Crash
Total Minutes: 294.17 minutes (4.90 Hours)

No ramp time listed between 550C to 560C.

Bandhu Dunham - 0.5 inch (12.7mm) thick:

I do not own Bandhu Dunham’s books but I have used the chart provided on this forum by nodice:
Source: http://www.talkglass.com/forum/attac...4&d=1206061572

Ramp from room temp 68F (20C) to 1050F(566C) at 107.50F per min. (9.13 minutes)
Soak for 15 minutes at 1050F (566C) (15 minutes)
Ramp 1050F (566C) to 910F (488C) at 18.75F per min (7.47 minutes)
Ramp from 910F (566C) to room temp 68F (20C) at 72.5F per min (11.6 minutes)
Crash
Total Minutes: 43.2 minutes (0.72 Hours)

Pyrex corning 7740 - 0.5 inch (12.7mm) thick:

Source: ASGS Fusion Issue #3 published in 1958

Room temp (20C) to 555C at 5C per min (107 min.)
Hold 30 min. at 555C (30 min.)
555C to 495C at 0.8C per min (75 min)
495C to 445C at 1.6C per min (31.25 min)
445C to room temp (20C) at 8C per min (53.125 min)
Crash
Total minutes: 296.375 minutes (4.94 hours)

Schott Duran 12mm thick:
Source: http://www.vidrasa.com/eng/products/duran/duran_pf.html
(bottom of page)

Room temp (20C) to 550C (?)
Hold 30 min. at 550C (30 minutes)
550C to 480C at 0.8C per min (87.5 minutes)
480C to 400C at 1.6C per min (50 minutes)
400C to 20C at 32C per min (11.875 minutes)
Crash
Total minutes: 179.375 (2.99 Hours)

Some notes:
It is interesting that the times to anneal roughly the same thickness of glass (12mm to 12.7mm) range from 0.72 hours to 5+ hours among the 5 above listed sources.

It is also interesting that the referenced article for Duran glass mentions that annealing time at 550C should NOT exceed 2 hours or there may be a negative result to the chemical stability of the glass, yet the Northstar table recommends 24 hours at annealing temp for a 6 inch (152.4mm) thick piece.

What do you all think?