Wool Dyeing: Copper Penny Blue

This dye substance is not a plant, but it would have been available in one form or other to many colonial home dyers. Known as “Copper Penny Blue”, this is a dye that does not need a separate mordant or even heat. The recipe is simple but it does take from 2-4 weeks for the process to complete itself. Fill a gallon jar to about three inches from the top with non-sudsing ammonia and put in: either 2 cups of pennies, OR a length of copper pipe OR a coil of copper wire. Screw the lid on tightly. Let this mixture sit for a week and watch it become a beautiful blue. At this point remove the copper , with rubber gloves, and put in the pre-wetted fleece to soak; varying the time gives different color effects. Some sources say it is also possible to do this with white vinegar instead of ammonia, but others say vinegar doesn’t work as well. Some recipes say to add a few teaspoons of salt to fix the color.

I’ve used this method several times with different results. One was a pale aqua, and the others various shades of icy green. I think it might be more reliable to use wire or pipe as the amount of copper in pennies these days is so small. Dyeing times, once the dye is made, have ranged from 1 day to 3 weeks of soaking the wool fiber. If you leave the jar in the sun it speeds the process somewhat. I would NOT try heating the mixture on a stove or fire, however.

My results have always been close to this.

Post revised 8/28/20

16 thoughts on “Wool Dyeing: Copper Penny Blue

  1. Does this ruin the pennies or copper piece? I am asking because I have a nugget of copper from a copper mine. Oh and some white wool that would love to be blue!


    • Coral Courtney says:

      Well give your reacting the copper with the ammonia you will have less copper in nugget then previously….How much less depends on the strength of the ammonia and the time the reaction runs.


  2. katknit says:


    In my experience, it leaves the copper brighter, but does nothing to damage it.
    The blue color is usually light aqua. Picture copper verdigris, in a light shade.



  3. I’ve heard that leaving the wool in the dye solution for too long can “eat” the wool. Have you seen this happen? Did you dilute the dye solution before you put the yarn in?


  4. Susan says:

    I have a recipe in Karen Casselman’s book (Craft of the Dyer) that calls for 1/3 cup of ammonia, 2 gallons of water, and 50 pennies to dye 4 oz of wool. Apparently, the ammonia doesn’t damage the wool, because it’s not heated. She also points out that the jar should be covered because the fumes are toxic.

    In terms of copper content, US pennies minted before 1982 are 95% copper (after that they’re 97% zinc). Canadian pennies minted before 1998 are 95–98% copper.


    • I’m not sure, Yvonne. If you used commercial fabric, it could have sizing or something in it. When I die fleece, it stays a white to beige color for a few weeks, then starts to go green. You can over-dye your fabric with another color if you want.


  5. All I can say is it worked for me, Knitmama. If you try it, please send a photo of your results, and if you like, I’ll post it here.
    Thank you for reading and commenting.


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