Recycled Glass Firing Schedules

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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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I have the same question. my tile saw is too fast and micro vibrations do too much damage.  Need to ask an electrician.  Some motors only work at full speed, and the rheostat will stress it out and burn it up.  If you find out, let me know.  


To get smoother edges (less chips) when cutting glass with a tile saw and glass/diamond blade, a friend suggested using a rheostat switch (similar to a dimmer switch) to slow down the speed of the blade.  Does this make sense?  I just don't fully understand the principle behind it.


I've been stressing that my kiln is not fast enough in the final ramp up to target--through the devit zone.  But I see here that you ramp slowly, 250/hr to target.  Doesn't that make a lot of devit?  

Mine goes up at less the 600/hr when on "full".  I see from some other sites that they go at 850/hr to target.  

I was thinking of upgrading for more power/speed, but maybe I'm O.K.  


I slumped some bottles in the bottle molds and had several very sharp spurs on the edges.  I knocked them off with the grinder so now I need to fire polish.  Can you recommend a schedule to fire polish the bottles so that I don't lose the shape?


Thanks, K



I saw the answer. Thanks 

GlassWithaPast moderator

@LongwellI share your concern about the motor burning up.  A better option (in my opinion) is to get a better saw and a better blade.  Here's a link to a newsletter where I contrast my old saw and blade with my new saw and blade.  Sometimes, you just gotta bite the bullet and buy the right tool for the job.

GlassWithaPast moderator

 @kellbwm I would use the schedule for fire polishing drinking glasses.  It will make the glass dark again.  It won't be hot enough to melt out polishing marks though, so make sure you're okay with whatever marks are there. The tricky part is getting the glass hot enough to fire polish, but not hot enough to move. 


@GlassWithaPast @Longwell  

Yeah, thanks, but we already knew about the option of buying brand new superior equipment.  Does anyone have an actual answer to the question?


 @GlassWithaPast I used your fire polish schedule and it move my glass some.  I need to either reduce the top temperature or time it's held.  What do you recommend?  I am never sure which to choose.




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