Recycled Glass Firing Schedules

Here are the super spiffy firing schedules that I use for fusing and slumping.  These work for both window and bottle (which have similar COE’s):

Full fuse firing schedule

(1/4″ window or 2 layers bottle glass, sheets, not frit!)

Ramp Rate (F) Hold Temp (F) Hold Time | Ramp Rate (C) Hold Temp (C)  Hold Time
300/hr 500 15 min | 148/hr 260 15 min
250 1100 10 min | 121/hr 593 10 min
250 1550 8 min | 121/hr 843 8 min
9999/hr 1060 20 min | 9999/hr 571 20 min
50/hr 940 0 | 10/hr 504 0
100/hr 740 0 | 38/hr 393 0
off to room temp | off to room temp

Slump firing schedule

(1/4″ or 2 layers bottle glass)

Ramp Temp (F) Hold Temp (F) Hold Time | Ramp Temp (C) Hold Temp (C) Hold Time
200/hr 500 15 min | 93/hr 260  15
250/hr 1100 10 min | 121/hr 593  10
250/hr 1385 3 min | 121/hr 752  3
9999 1060 20 min | 9999 571  20
50/hr 940 0 | 10 504  0
100/hr 740 0 | 38 393  0

 

These are the firing schedules I use in the side fire Skutt kiln.  The top fire Denver is the same, EXCEPT, the top temperatures are 1530 F (832 C) for fuse and 1340 F (726 C) for slump.

 

You can go faster and hold for less time with very small pieces, and slower ramps with longer holds for very large/thick pieces.

Pot Melt/Casting Schedule (3/8″ final thickness) (9.5mm)

Ramp Tem (F) Hold Tem (F) Hold Time | Ramp Temp (C) Hold Temp (C) Hold Time
300 500 40 | 148 260
300 1100 40 | 148 593
350 1850 18 | 176 1010
9999 1060 45 | 9999 571
50 850 0 | 10 455
100 650 0 | 38 398

This is a very basic casting schedule.  If you change the final thickness, you must also adjust the hold time on the annealing.

Keep in mind that every kiln is different, so start here and see what you get.  If your edges are still square, go hotter.  If you’re getting severe needling around the edges, your top temperature is too hot.

Please note that these schedules will not work for frit in jewelry molds, you need a much higher temperature for that type of firing.

Happy experimenting!

 






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