The revival of European glassmaking skills came from Venice through commerce with the Eastern Roman Empire. The Venetians made discoveries and innovations of their own, eliminating all accidental colorizers from a glass melt by adding glassmaker’s soap - used by glassmakers to remove a green color produced in glass by iron salts. This resulted in gray glass, which offered less transparency than that of the slightly tinted glass. But because the amounts of the original colorizer and its antidote were small and the thickness of the finished glass was slight, the loss of transparency was less noticeable than the unwanted color would have been.