Your ware is fairly thick. It was already vitrified in a previous firing. It now must climb and fall through quartz and cristobalite inversions during a decal firing. The firing schedule provided by the decal supplier ramps up very quickly. The result? A cracked piece.
This process of printing a design (using ceramic inks) onto a film coated decal paper, drying it, transferring the film on to the fired ware. But beware of a problem they do not mention.
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