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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