Dye Project: Red Cabbage

For this home dyeing project we're working with red cabbage (Brassica oleracea), also called purple cabbage, red kraut, or blue kraut. The cabbage leaf color depends on the pH of the soil. In acidic soils the leaves are reddish, in neutral soils they are more purple, and in alkaline soils they are greenish-yellow. We'll be dyeing more white cotton dish towels, and using the experience we gained when dyeing with black walnuts  (see Dye Project: Black Walnuts). We'll actually try two projects – the first is to dye the fabric with a cabbage dye bath, the second is to change the pH value of the dye bath to see how it changes the fabric dye results.





Red cabbage is typically available year round at the grocery stores in the San Francisco Bay Area. I picked out a couple of dense red-purple cabbage heads and chopped them up, using one cabbage head for each project. The color pigment is so beautiful (but of course the color of the source does not predict the end result)!

Chopped head of red cabbage

Cotton dish towels pre-washed and treated with a salt mordant

To prepare the dish towels for the dyeing process, I washed the fabric in the washing machine, and treated the fabric with a salt mordant. I boiled the fabric in a mixture of 1 part salt to 16 parts water (with additional water to cover, as needed) for an hour. This is described and demonstrated in Mordants and Fixatives. I didn't scour the fabric.

Straining the dye from the cabbage pulp

Purple cabbage dye

I used our patio for my outdoor studio (cabbage is quite pungent). To a gallon of water I added the chopped leaves of a head of cabbage, plus 1 tablespoon of salt for every 1/2 cabbage as an extra mordant, then simmered the mixture for about half an hour. These proportions are recommended by Samantha James of All Natural Dyeing (search for red cabbage).  After boiling, I strained the mixture through cheese cloth and returned the dye to two pans (splitting it so that each pot could easily accommodate three dish towels). I brought the dye bath back to a boil, immersed the dish towels,  reduced the heat, and let them simmer for an hour. I let the towels soak over night to deepen the blue color.

Let the towels soak in the dye over night

Rinse the towels thoroughly in water

The next day I rinsed the towels until the water ran clear. The fabric lost quite a bit of  color in the process, but they were still a lovely shade of blue. I hung the towels to air dry, then ran them through the washing machine to make sure the color was set.

Batch 1 - dark blue towels after rinsing

This seemed like a successful project, but, several months later, I retrieved the dish towels from the drawer in which they were stored to find they had faded to a dingy white! The short list of possible causes:

• I did not scour the fabric, so waxes, oils, sizing, or other treatments may have remained on the fabric even though I pre-washed the dish towels. Any deposits on the fabric surface would prevent the dye from bonding with the fibers.
• Salt may not be an adequate mordant for cabbage. 
• Cabbage dye may not be colorfast.

After several months, the towels had faded to a dingy white!

For the second project I changed the pH value of the dye bath to see how it would change the color of the fabric. I used the process described above to create the basic dye, and then split it between two pans.

• To one pan I added 2 tablespoons of white vinegar to make the dye bath more acidic (should turn the bath more pink).  
• To one pan I added 1 tablespoon of ammonia to make the water more alkaline (should turn the bath more blue).

Left: vinegar added to make the dye bath more acidic.
Right: ammonia added to make the dye bath more alkaline.

Left: after the initial chemical reaction the towels appear pink-blue.
Right: the towels appear more blue.

The chemical reaction in the dye bath was very promising. You can see how the pan on the left seems to show both pink and blue, and the one on the right first turns an (unexpected) bright green and then calms down to a blue.

Batch 2 - after rinsing, all the dish towels are pale blue.

After simmering the dish towels in the two dye baths and then rinsing the fabric until the water ran clear, I ended up with six blue dish towels!

And, several months later, these blue dish towels had faded to a dingy white just like the first batch! This was a little disappointing, to end up with 12 dingy white dish towels (especially when the initial blue color was so appealing, and the chemical reaction in the dye bath was so promising)!

Several months later, all 12 of the dish towels are dingy white!

But that is part of the fun (and pain) of dyeing with plants. For my next experiment, I plan to scour the dish towels (and not just pre-wash them), and to use stronger mordant like a colorless tannin such as Gallnut, Tara, or some Sumacs (described in the Maiwa Guide to Natural Dyes, see the Mordants section, under Tannins).