Final Heating

What it does:

Heats the kiln as fast as possible to get the glass to fusing temperatures.

The Final Heating and the Process Stage (more later) share a single firing segment.  Here is an example of a final heating step for the Final Heating Phase:

Firing Schedule - Final Heating


Things to consider:

By the time we get to our final heating segment we are well past the point at which we need to worry about thermal shock so there is no need to slow down.

In fact, our glass has now entered the temperature range in which devitrification can occur. We want to get to our top temperature as quickly as possible, do what needs to be done, and then get out of the devitrification-friendly temperatures.

Full Fuse

Hello - I am new to fusing and this site.  I have a silly question, what does FULL mean when you have a target of 1515?  Am I to set the rate to 1515/hr?  Still learning!!!

FULL in a firing schedule....what does it mean?

When you see FULL written out in caps like this in a firing schedule, usually at the final heat ramp or the cool to anneal temp that follows the highest temp you are aiming to go to, it means to go "as fast as possible", or at least at as high a degree/hr. rate that your kiln can manage. Most kilns with digital controllers will let you just hold the increase button in while the digits spin to the highest it is rated for. My top "rate" is 1800- degrees fahrenheit. It really just means that you want to get there fast. In the case of the drop to anneal temp, the reasons are two fold: 1) to freeze: the movement of the glass at the point that you want it to be, so that it doesn't change on it's way down to anneal; and 2) to get yourself out of Dodge...the devit capital of glass.

The old school way to accomplish this was to "flash vent", or actually raise the lid of the kiln for a short period to allow a rapid release of heat. The new thinking discourages from this practice, because it is hard on your kiln's elements and fire brick, especially in the lid. Also, your shelf could thermal shock and crack. However, the glass will be fine. I am old school. I started doing this way before controllers were around, and I still do it when I need to really observe/manipulate/freeze the movement of my work. Most of my pieces are one-of-a-kind, so there is no magic schedule that will guarantee results.

If you do decide to flash vent, be very careful. The best way is to turn off the kiln, while you are doing it, but it is not always convenient to re-start it and speed ahead in your program to ramp back to anneal.

At any rate, safety gear is required. I wear an aluminized kevlar apron, 22" high Zetex gloves, cotton clothes and bandanna, and a full face Didymium II Gold coated face shield made by Oberon.  Don't flash the lid to high, or push air downward too rapidly, and stop flashing as soon as you drop below 1200 degrees and you are sure it is not re-heating on its own from stored heat.

Hope this helped. Good luck!

Cynthia Ann Swan, Terra Pax Studio, Los Angeles, CA

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