Happy Easter everyone!!
John........if, as you have thoughtfully speculated, the SOs and STs in question were actually color compatibility test mibs, it would have made good business sense for the plant to save and catalog them as color combo marble examples that either worked or didn't work, as part of exercising good QC and product development practices. If management wanted to try a new glass combo, they would have their fully documented test mib samples to guide their efforts. It would be reasonable for there to have been quite a collection of these compatibility sample marbles (and probably marble halves for formulations that did not work out), generated and cataloged over time. When the plant was closed, what would have happened to these samples? Regardless of whether a cache of these mibs may have been found in the ground or in someone’s attic, this hypothetical could explain how they may have surfaced as a cache of mibs that had never been previously seen before.....Bill