That sounds good.  I called my spouse, who tells me that she fires bisque to
1800 F and glaze to 2280 F (I think this is for a porcelain body.  She mixes
her own glazes in a messy process that I know nothing about except "don't
inhale").  So I would think putting a few sherds in firings might tell us
something.  She also said including historic sherds wouldn't hurt her wares
so long as the old stuff didn't melt, but that's easy to contain.  I will
see if the State folks here in NC are willing to sacrifice a few sherds to
the furnace (Hey, come on, Linda, you'll get 'em back).