Gaffer® Casting Crystal Annealing Schedules. Semi-Open and Open Forms *

Thickness (inches)
(mm)		 Anneal Soak at
824oF
at 440oC		 Initial
Cooling
Rate
(oF/Hr)
(oC/Hr)		 Initial Cooling Range
(oF)
(oC)		 Second Cooling Rate
(oF/Hr)
(oC/Hr)		 Second Cooling
Range
(oF)
(oC)		 Final Cooling Rate**
(oF/Hr)
(oC/Hr)		 Final Cooling Range
(oF)
(oC)		 Total Elapsed Time
.5 in 
12 mm		 1.0 hr 120
67		 824 - 694
440 - 368		 240
133		 694 - 604
368 - 318		 1200
670		 604 - 75
318 - 24		 2hrs 53mins
.75 in
19 mm		 1.5 hr 52
29		 824 - 679
440 - 360		 104
58		 679 - 589
360 - 310		 520
290		 589 - 75
310 - 24		 6hrs 6mins
1.0 in
25 mm		 2.0 hr 29
16		 824 - 664
440 - 353		 58
32		 664 - 574
353 - 303		 290
160		 574 - 75
303 - 24		 10hrs 44mins
1.5 in
38 mm		 3.0 hr 13
7.2		 824 - 626
440 - 330		 26
14.4		 626 - 536
330 - 280		 130
72		 536 - 75
280 - 24		 25hrs 30mins
2.0 in
50 mm		 4.0 hr 7.8
4.3		 824 - 594
440 - 312		 15.6
8.6		 594 - 504
312 - 262		 78
43		 504 - 75
262 - 24		 45hrs
2.5 in
60 mm		 5.0 hr 5.2
2.9		 824 - 566
440 - 296		 10.4
5.8		 566 - 476
296 - 246		 52
29		 476 - 75
246 - 24		 2 days 23hrs 
3.0 in
75 mm		 6.0 hr 3.3
1.8		 824 - 524
440 - 273		 6.6
3.6		 524 - 434
273 - 223		 33
18		 434 - 75
223 - 24		 5 days 4hrs
3.5 in
88 mm		 7.0 hr 2.5
1.4		 824 - 486
440 - 253		 5.0
2.8		 486 - 396
253 - 203		 25
14		 396 - 75
203 - 24		 7 days
4.0 in
100 mm		 8.0 hr 1.8
1.0		 824 - 454
440 - 234		 3.6
2.0		 454 - 364
234 - 184		 18
10		 364 - 75
184 - 24		 10 days 15hrs
4.5 in
113 mm		 9.0 hr 1.6
0.9		 824 - 417
440 - 214		 3.2
1.8		 417 - 327
214 - 164		 16
9		 327 - 75
164 - 24		 12 days 14hrs
5.0 in
125 mm		 10.0 hr 1.3
0.7		 824 - 383
440 - 195		 2.6
1.4		 383 - 293
195 - 145		 13
7		 293 - 75
145 - 24		 17 days 4hrs
5.5 in
138 mm		 11.0 hr 1.1
0.6		 824 - 347
440 - 175		 2.2
1.2		 347 - 257
175 - 125		 11
6		 257 - 75
125 - 24		 21 days 6hrs
6.0 in
150 mm		 12.0 hr 0.9
0.5		 824 - 312
440 - 156		 1.8
1.0		 312 - 222
156 - 106		 9
5		 222 - 75
106 - 24		 27 days
8.0 in
200 mm		 16.0 hr 0.47
0.26		 824 - 172
440 - 78		 0.94
0.52		 172 - 82
78 - 24		 -
-		 -
-		 62 days

*  Based on: Schedules for commercial annealing of ordinary ware. Corning Glassworks. Corning N.Y. 1950. For forms that are able
    to cool reasonably equally on all sides.
** Obviously cooling rates of thinner pieces are faster than ordinary kilns would lose heat. In those cases the kiln can be allowed to
    cool at its normal rate.
 
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