"It was more common, in glassmaking or enameling treatises, to focus attention to chemistry on the creation of coloring materials, particularly the glass-fondant-metal combinations. reference An underlying belief was that firing would, in addition to melting the as-yet unformed color, exclude potentially harmful airs, as was the case in other painting practice. 37 Sometimes a description suggested that the vitreous color or coating held itself in place as a layer constricting the whole."