Sorry to be dragging my feet on this subject. I have to confess to finding it a little tedious. For me, technical information is like lifeboat maintenance on the Titanic. No one really cares about it (myself included) until something goes wrong.

Then you’d like to know that the equipment doesn’t have holes in it.

Last week I went over basic compatibility testing as it was established at Bullseye and has been practiced in our field, with little or no variation, for the last 25 years. Whether that test is being performed within the factory or the artist’s studio, it is not - and never has been - a measurement of the so-called COE. What is measured is the strain that exists at the interface between the chip and the base glass.

WHAT STRESS?! By Bullseye’s factory standards the four chips on the far right of this bar are considered incompatible. Chips 1570 and 1572 are low relative to the base clear. Chips 1573 and 1580 are high relative to the base. Compare this bar with one in which many of the samples are very obviously out-of-compatible range
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Third, and last, on my list of “Unbeautiful Things” is the manner in which kilnforming is being marketed today. I have some pretty strong opinions on this, so if you’re not ready for another rant, you may not want to keep reading.

This is what STRESS looks like. It happens when glasses that are not “compatible” are fused together. Understanding it is the foundation of glassforming.

IMO reducing a rich and fascinating field to a litany of assurances that success will come from buying a glass with a “wider margin of error” and a kiln that a dog can program does a disservice to the many exceptional artists who have worked to advance the reputation of the medium and to the beginners who deserve to be educated, not harvested.
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