Open Fusing Kiln
At what temperature is it safe to open fusing kiln? While firing up your piece, it is common to peek once the piece has reached a temperature of over 1000 degrees Fahrenheit. Make certain to wear your safety glasses when attempting this procedure.
Glass is brittle between room temperature and 1000 degrees Fahrenheit. Do not open your kiln below 1000 degrees Fahrenheit. At above 1000 degrees Fahrenheit, the glass is warm enough that it is now safe to open fusing kiln and view the glass. Always wear eye protection when observing the fusing glass in the kiln. The blistering air coming from the kiln can harm unshielded eyes!
If your kiln is made out of thick fire bricks and it cools off slowly you are able to turn it off and then just allow it cool down to room temperature. However, if it is a ceramic fiber unit you will need to keep the glass fusion reducing temperature at a rate not quicker than approximately 300 degrees Fahrenheit per hour.
Never bring your glass out of the kiln until it is actually room temperature. Exposing the glass to cooler air when it is hot and brittle will result in thermal shock to the glass.
If you view hot objects in a kiln on a regular basis, through the peephole or opening the door or lid, wear glasses with IR and UV protection. You have only one set of eyes, so protect them at all times. The primary reason for this protection is that the red-hot glass gives off infrared rays. Extended exposure to these wavelengths can cause cataracts. When you open fusing kiln, wear the proper type of glasses to help stop these infrared rays.
The least expensive type of glass to purchase is welder's glasses. They can also be purchased in local hardware stores. Try purchasing colobar, the number 3 welder's glasses. Welder's glasses are adequate for glass fusing uses.
How long do you flash vent when fusing? If
your piece, watch the pyrometer dial. Vent for just a few seconds until the temperature reads around 1100 degrees Fahrenheit. Then close the lid of the kiln and allow it to cool off at approximately 300 degrees Fahrenheit per hour.
It is safe to open the kiln once the temperature has reached 100 degrees Fahrenheit or under. Always remember to shut off your kiln and unplug it when not in use.
Whenever you would like to re-fire your glass a second time, whether to slump it or add more to the object, remember that it's now doubly as dense and can only be heated at about 450° per hour. The rule of thumb here is to heat up half as fast as the first firing and cool down half as slow.
Return from this page to one of the following pages:
Glass Fusing Problems
Fusing and Slumping
Open Fusing Kiln to Glass Fusing Made Easy