I love experimenting with natural dyes and thought it’d be fun to make one using freshly picked berries. Blackberries create a color that ranges from bluish lavender to purple-gray. This isn’t really considered a dye (technically it’s a stain), but I’ll show you how to use potassium aluminum sulfate or table salt as a mordant. Since blackberry dye isn’t a true dye, the color is not as pigmented and permanent as others. I always recommend using natural fabrics, as they retain dyes the best. I typically work with 100% linen, wool and cotton. My son loves this project since going berry picking is a Summer tradition of ours and we often have an abundance of berries all season.

Materials:

– fabric: natural fibers such as cotton, linen, muslin, silk and wool. Read more on how to choose textiles here. I also dyed this cotton string market bag that is 100% cotton including the thread. If you’re dyeing something that has stitching make sure that the thread is 100% cotton as well, otherwise the thread will not dye. When dyeing natural fibers keep in mind that shrinkage can occur.
– two large pots (at least one has to be enamel, stainless steel or other nonreactive metal. If you are using the potassium alum mordant you will need a pot that you can dedicate to dyeing or crafting)
– fine strainer (mesh, cheesecloth, etc)
– blackberries (I used a ratio of 1 part berries to 2 parts water- 2c berries to 4c water for the amount of fabric I was dyeing)
– optional mordant: potassium aluminum sulfate or table salt

Instructions for making and using blackberry dye:

Step 1: How to mordant fabric.

Prepare your fabric by pre-washing in hot water with a neutral detergent. To use potassium aluminum sulfate as a mordant, calculate the amount of potassium alum you will need to mordant– generally you’ll use an amount that is 15% the weight of fabric (WOF). The mordant will help your fabric to retain the dye and when you alter the pH the color will change. Using potassium alum will increase the acidity of the dye, therefore decreasing the pH which will result in a more vibrant color. Dissolve the potassium alum in warm water, making sure that you have enough water to fully submerge your fabric. Soak your fabric for an hour in the alum mordant bath.

If you are dyeing with children and using cotton fiber you can opt to use salt as a fixative instead. Table salt aka sodium chloride is a neutral salt and therefore will not decrease the pH so it won’t brighten the color as compared to the potassium alum. The salt mixture will simply act as a fixative to help the color penetrate the fabric. To use salt as a mordant, create a ratio of 1 part salt to 16 parts water in your extra pot. Make sure that you have enough water to fully submerge your fabric. I used 1/2 cup salt to 8 cups water. Place your fabric into the water and simmer for an hour. Once it is finished, rinse the fabric in cold water and squeeze out excess water. Set aside.

Step 2: How to make blackberry dye.

Combine the blackberries and water in your pot (nonreactive metal) and heat on low. Bring to a really low simmer and let simmer for 20-30 minutes. Be careful to not boil or overheat the mixture. At the midway point I like to lightly mash the berries a bit to help release some of the juices. Remove from heat, strain berries from the liquid with a fine strainer then return liquid to the pot. You can then add the berry mash (after it has been cooled) to your compost — or it can be fed to your chickens if you have them!

Step 3: How to dye your fabric with blackberry dye.

Submerge your wet fabric into the dye bath making sure that your fabric is completely covered. I’m using 100% cotton and linen. Heat gently on low for 1-2 hours then remove or let sit overnight. Stir every so often to agitate the fabric and to make sure there aren’t any air bubbles trapped in the fabric that will cause uneven coloring.

When the color is to your liking (keep in mind that the final color will be several shades lighter once washed) rinse out excess dye and hang to dry indoors or out of direct sunlight. The dye bath will give off more of a pink-purple color, but once you rinse the fabric you’ll see that the fabric has taken on a purple-lavender-gray color. I like to leave them on the drying rack for a couple of days before drying them through a delicate cold cycle and hanging to dry again.

A note on washing: Plant dyes are PH sensitive so you’ll need to use a bio soap such as Seventh Generation or Ecos. Natural dyes will fade a bit but the fabric will hold a good amount of color if cared for properly.

Here’s a comparison of a few different fabrics dyed with blackberry dye.
Left: 100% cotton market bag (using potassium alum as a mordant)– freshly dyed, washed and air dried
Right: 100% cotton and 100% linen (using table salt as a mordant)– both freshly dyed, washed and air dried

This post has been updated August 2021 to include additional techniques and improvements.

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