The measurement of the propensity of glass contact refractory materials to give rise to gas bubbles in the melt (known as “blistering”) is of crucial importance especially for distribution channels (feeders), where any bubbles nucleated within the glass have less time to be reabsorbed in the melt, or to reach the surface and be released into the atmosphere.

To evaluate the blistering tendency of a refractory, SSV carries out specific tests following a test method defined by the ICG Technical Committee TC11. On the basis of the experimental results, a qualitative performance index is obtained: an excellent material develops less than 10 bubbles/g glass (index = 1), while a poor material can release more than 1500 bubbles/g glass (index = 4).