Copper

Description

Called “Blue Vitriol” in old dye books.  Copper can be used as either a pre-mordant, at ½ ounce per pound fabric (3%), or as an after-mordant modifier, where you leave it to soak and take it out when the color has changed “to taste”.

Please use copper responsibly: do not dump your mordant bath, but re-use it according to the general formula of add only ¾ the usual amount, (assume ¼ of what was added for the last mordanting is still there).