It’s not easy to dye cotton fabric a washfast and lightfast blue with natural dyes (except with indigo and woad).
After reading that iron in the soil makes hydrangea flowers more blue, I wondered if iron mordant could help to fix the blue color to cotton fabric. And after some experiments with different mordants and modifiers and various natural blue dye materials, I’ve finally found out that red cabbage dye + iron mordant produces a beautiful washfast and lightfast blue! Yay!
So in this tutorial I’ll show how to dye cotton and viscose rayon fabric blue with red cabbage and DIY iron mordant.
How To Dye Cotton Blue With Red Cabbage (DIY Iron Mordant, Cold Method)
- red cabbage
- prewashed fabric or yarn *
- DIY iron liquor
- pot and bucket
- rubber gloves
* I used unbleached and white cotton fabric, off-white rayon chiffon and white cotton yarn.
Wear rubber gloves and old clothes to protect your skin and clothes!
DIY Iron Mordant
Pour DIY iron liquor into a bucket.
Related: How To Make DIY Iron Liquor Mordant
Dilute iron liquor with enough water so that you can submerge the fabric. Wet the fabric and yarn with water, then submerge it in the iron liquor solution. Let it soak for some seconds in the iron mordant. The iron mordant dyes the fabric beige or brown.
Squeeze out excess mordant. Let the mordanted fabric dry or use it right away.
Red Cabbage Dye
Chop red cabbage and put it in cold water because natural blue colors – anthocyanins – are heat-sensitive.
I used just the limp outer cabbage leaves – the rest we used for eating.
Let the red cabbage soak till the water turns dark blue like ink. Mine took about one day.
Dyeing The Fabric
Put the fabric or yarn into the dye solution. Add water if necessary: more water won’t weaken the dye solution, but the fabric will dye more evenly. Stir the fabric occasionally. Let the fabric soak as long till you like the color – bear in mind that wet fabric is darker than dry fabric; also the color will bleed during the first wash.
I let the fabric and yarn soak for about 12 hours.
Rinse In Cold Water
The fabrics and yarn on the left are already rinsed in water. The cotton fabric and yarn took the color better than the viscose rayon which only turned pale blue.
Here’s how the fabric and yarn looked after the washing machine.
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