Firing schedules for thick pieces of glass

It is very important to get the correct firing temperature for your glass projects so that you don't open your kiln, thinking your project is completed, only to discover a broken disaster!  In our own glass studio, we have discovered, the hard way, that we have to slow down our firing schedule when fusing our glass bottles together.  You will find that you not only need to slow down the heating up process, but also the cooling down part too.

We found these great tables below, made by System 96 glass.

*Please note: the schedules below are guidelines only, not strict rules. Times and temperatures may be adjusted based on the nature of your project. To use these schedules for slumping, set the target temperature in the "variable" step to 1235 - 1250 depending on your desired results.

1/2 -inch Thick Step Rate(per hour) Target Temp. Hold(minutes) 1 100 300 15 2 250 1050 10 3 *variable 1500 desired effect 4 as fast as possible 950 90 5 100 800 10 6 300 100 0

*This rate varies based on what you want to accomplish. For instance, heat faster to fire polish, slower to minimize air bubbles.

1 -inch Thick Step Rate (per hour) Target Temp. Hold(minutes) 1 100 300 15 2 200 600 15 3 300 1050 15 4 *variable 1500 desired effect 5 as fast as possible 950 120 6 30 800 15 7 50 700 10 8 250 100 0

*This rate varies based on what you want to accomplish. For instance, heat faster to fire polish, slower to minimize air bubbles.

1.5 -inch Thick Step Rate (per hour) Target Temp. Hold(minutes) 1 100 300 25 2 200 600 25 3 300 1050 20 4 *variable 1500 desired effect 5 as fast as possible 950 180 6 12 800 15 7 24 700 10 8 120 100 0

*This rate varies based on what you want to accomplish. For instance, heat faster to fire polish, slower to minimize air bubbles.

2 -inch Thick Step Rate (per hour) Target Temp. Hold(minutes) 1 100 300 40 2 200 600 40 3 300 1050 30 4 *variable 1500 desired effect 5 as fast as possible 950 240 6 8 800 30 7 16 700 30 8 65 100 0

What happens if your piece of glass is thicker than your lead came?

Have you ever been working on a leaded glass window and discovered that you used such a thick piece of glass that it is too wide to fit into the channel of your lead came?  This does happen!  Typically this happens when you are using a piece of glass that has a very deep texture.  You will notice that a piece of Drapery glass has a lot of very thick areas.

So, to resolve this problem, you will need to use wide heart came on that thick piece of glass.  You don't need to use the wide heart came on the entire stained glass window, instead you can use it only around that thick piece of glass.  And continue using the regular heart came for the remaining window.   When shopping for came, it is possible to find wide heart came in lead, zinc and brass.

If this same situation arises when working with copper foil, the remedy is quite simple as well!  You'll need to foil one side of the piece, then flip it over and foil the other side, allowing the foil to overlap in the center area of the edge of the piece of glass.  Later, when the piece is soldered in the stained glass window or suncatcher, this piece will be as secure as a regularly foiled piece of glass!