Blonde Revival (detail) Jason Lindell

System 96®: Common Questions and Answers


Go to the Source for Help with Individual Products

If you have questions or issues with an individual System 96 product, please consult the company that produced that product. Both Spectrum and Uroboros produce sheet glass. There is a “U” or “S” following every sheet glass product shown on this site denoting the company of origin. In other product categories, the initial page of the category will identify which company produces that line.


What’s the difference in kiln forming with “90” and “96”?

Really very little. What you learn with one glass will largely apply to the other. System 96 is a lower temperature glass — that is, it takes less time / heat for System 96 products to reach a given viscosity than it does common COE 90 products. Understanding this, and looking over the System 96 Firing Guidelines, a kiln crafter will quickly adapt to the differences.



Is devitrification a problem with System 96 glasses?

All System 96 products have been specially formulated to resist devitrification. That, plus compatibility testing, makes them ideal for use in the kiln arts.


Should I test?

Testing is your best teacher. You’ll discover subtle nuances in different glasses, monitor color shifts, and be better able to predict various characteristics that may result from the fusing process. Plus, because our equipment and procedures differ from yours, you just might uncover a set of circumstances in which our “Tested Compatible” glasses don’t act as expected in your system of variables. Better to discover that in testing than in a disappointing project.


Do you offer technical support?

We encourage you to first browse our published information (all available free of charge and all accessible here on the System 96 web site) to see if your problem has been addressed. You might also pose the question to your peers on the excellent bulletin board at the independent kilncrafter’s web site, You may e-mail your questions to us at Spectrum and we will do our best to assist.


What’s compatible with System 96?

Let the red System 96 logo be your guide to products that have been “Tested Compatible” within the System 96 program. Please note that that products labeled as simply “COE 96” may not actually be compatible with true System 96 products. If in doubt about a product, ask your supplier!





How can I prevent bubbles from forming between the kiln shelf and the bottom layer of glass?

This problem is gas. Small amounts of moisture in the kiln shelf or shelf primer may be turning to steam at high temperatures. Or, some organic material (dirt, filings or other debris) are burning and gassing off at fusing temperatures. The best way to prevent these types of bubbles is to use PAPYROS® Kiln Shelf Paper between the shelf and the glass. The paper is air-permeable and will allow more air to escape than in direct-shelf contact.



How do I avoid kiln wash sticking to my piece?

More than likely, your firing temperature is too hot. Try experimenting with your fuse cycle. Either go to a higher temperature for a shorter amount of time or try a lower temperature for a longer period of time.  PAPYROS® Kiln Shelf Paper is a great alternative to primer and you won’t have to worry about it sticking to your piece.