Natural Dyes: Black Walnuts

I have been really interested in natural dyes this year. Remember my Easter egg dye experiment? I used onion skin and herbs to color eggs and they came out rather beautiful.

I am taking a class this summer designed for teachers that is all about “materials science.” I am learning a lot of cool stuff and performing pretty interesting labs that have to do with polymers, magnets, solar panels, dyes, wood, paper, and so many other  cool science things. We spent a whole day on dyes (natural and chemical) with the Chemistry professor and part of a day using natural dyes with the Botany professor. Needless to say… I was excited!

I had to do an assignment comparing two different materials dyed with black walnuts – silk and cotton. Here’s the recap of how to dye using black walnuts and the results for the different materials:

Here is what the black walnut tree looks like. The walnuts start off really green and hard and turn brown and fall to the ground as they mature. You want to use the walnuts that have turned brown and have fallen on the ground. Fall is the perfect time to harvest them, so you might need to plan ahead if you want to use them for dyeing.

You’ll need to crack open and remove the husk from the hard shell inside. There is a dark substance between the husk and the nut shell that is going to provide you with the dark brown color for the dye.

I think the best way to crack the walnut it is smash it between two heavy rocks, boards, etc. I chose to use some bricks from my back yard. They made crushing the walnuts pretty easy. DO NOT try to cut the nuts with a knife, they are very hard and you can easily slip and cut yourself!

Here are my crushed up black walnuts. I am using 16 walnuts to 16 cups of water for my dye. This will give you a nice brown color, you can add more or less depending on how dark you want the dye.

In the kitchen… bring the water and nuts to a gentle boil in a pot large enough to add whatever you are dyeing. Once it is boiling, give it a stir and reduce the heat down to medium heat. Allow the liquid to gently simmer for about 15 minutes. While the walnuts are simmering in the water, prepare your material to be dyed. Turn on the ventilation fan on your stove! The walnuts give off a strong odor when boiling.

I am using an old 100% cotton t-shirt and 100% silk scarf. Which of these materials absorb and retain the brown dye better? There’s only one way to find out…

Soak your material in warm water and ring it out.

if you want to make patterns on your shirt of scarf, you can do so by folding it in different ways. I am going to try to make a classic swirl pattern on my shirt and scarf. Here’s how its done:

Pinch a small area of the shirt/scarf and twist it in a circular motion. You can use rubber bands to secure your twist… but I used bakers twine and tied up my twisted patterns on the t-shirt to hold them in place. I think the bakers twine was actually easier and held better than the rubber bands, so you might want to try it!

I made about 5 twists on the shirt, all secured with the twine.

I did the same with the scarf.

Submerge the prepared shirt/scarf into the black walnut dye and make sure they are covered by the water.

You can leave your project in the dye anywhere from 2 hours to a day. Depending on how dark you want your piece of art work to be.

I left mine in the pot over night and through out the day for 18 hours! Here’s what it looks like when it comes out:

I placed my shirt in the sink and rinsed it while I was cutting the bakers twine off. I didn’t want to make a big mess and splash the dye all over the place, so the sink was a good place to remove the twine.

Rinse the shirt/scarf thoroughly with water until it runs clear.

Check out your pattern!

Both the t-shirt and the scarf look pretty good. I think the silk really took up the dye better than the cotton.

Wash your items in the washing machine… by themselves! You may get brown dye on other items if you wash the dyed clothing with other clothing at first.

After the wash, it appears that the silk did take up the dye better than the cotton. Are you ready for the explanation? I might get a little nerdy…  but I’ll keep it simple.

Silk fabric has the ability to form ionic bonds with the dye. Ionic bonds are strong! Silk also has more places in its chemical structure to which the dye can bond. What does that mean? That means your dye won’t wash out of the fabric very easily and it will appear to have a richer color for a long time.

The cotton fabric forms hydrogen bonds. These are not as strong as Ionic bonds. So your fabric might fade from a lot of washing and your color might not appear as rich.

I haven’t tried this yet but if you add a stronger acid (like vinegar) to your dye bath, the brown color will be altered a bit. You can also add a base to change the brown to a different hue. I still need to do some research on that to figure out what kind of household acids and bases I can use.

It’s amazing how many natural things you can dye fabrics with! I’ll be sharing some of my other natural dye experiments as I work through them. I have a white tank top that I am going to try dyeing with turmeric next. There are so many foods and plants that will turn things beautiful colors. Leave a comment if you have tried dyeing fabrics with other natural dyes – I am always looking for new ideas!


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