First a disclaimer: no pennies were harmed in the process of dyeing this fabric. Craft of the Dyer: Colour from Plants and Lichens by Nova Scotia dye expert Karen Leigh Casselman is my main dye bible. Most of the dye recipes are for plants found in North America, but Casselman offers two offbeat mineral dye recipes with copper pennies and clay as the dyestuff. This summer I'll try the clay recipe which is very messy. Copper penny blue was manageable in my laundry room. Dawn MacNutt adapted the recipe from a Salish Weaving book and shared it with Casselman. The recipe is simple: combine ammonia, water, pennies, and fabric in a sealed glass jar and let sit for a few weeks. Ammonia is dangerous to work with, so I wore a respirator, safety glasses, a splash shield, a dye apron, and chemical gloves when I handled it. I immersed 417 pennies in a solution of one-third cup of ammonia and two-thirds cup of water, and then added more water and fabric. I let the mixture sit for 3 weeks. The pennies are not harmed in any way and can be used for the usual purposes once they are rinsed at the end of the dye process. The book goes into more detail than what I have given here.
As you can see, the copper penny ammonia dye solution yielded a grey blue on cotton fabric. Next I'll add some pale onion skin dyed fabric to see what shade of green I get.
Pennies are no longer made of 100% copper. Canadian pennies were made of copper until 1996 and U.S. pennies were made of copper before 1982, so I bought $10 worth of pennies from the bank and sorted them. Ten dollars (1000 pennies) yielded 415 copper pennies, less than half.
I haven't yet read India Flint's dye books – I'm planning to get my hands on them this Spring. Casselman's book is extremely informative but lacks pictures. Some of the newer dye books have gorgeous pictures that are beautifully styled but basic information like light-fastness is missing.