Fabric Preparation

Keeping it easy with cotton

We stick to white cotton T-shirts for most of our dyeing. They’re easy to find, affordable, and simple to work with. You can also try cotton shirts, cotton fabric (calico, muslin), or fibres such as linen, hemp, or bamboo.

If using fabric by the metre, prewash first—some, like calico, can shrink by 10% on the first wash. (Dressmakers, this is your reminder: wash before you measure twice and cut once!)

Watch the Thread

Ready-made clothes are often stitched with polyester thread, which won’t take dye. If you’re sewing from scratch and want an all-over colour, use 100% cotton thread. (Ask me about the Broderie Anglaise incident sometime… let’s just say I ended up with a green and white top. Not quite what I had in mind.)

Check Your Labels

Also check fabric labels—poly-cotton won’t take up natural dyes properly and isn’t suitable.

Keeping It Simple

We’ve kept things cotton-based here. Wool and silk (protein fibres) need different methods—even if you’re using the same plants.

 

Scour / Wash

Scour and wash mean the same thing—basically, wash first. There are natural substances (and additives from the milling process) that protect the fabric—but they also stop dye and mordant from bonding properly. For cotton T-shirts, a hot machine wash with a spoonful of baking soda does the trick.

Mordant or Binder

A mordant forms a chemical bond between fabric and dye and gives the best colour fastness. A binder (like soya milk) forms a mechanical bond—less permanent, but still lasting. The colours may shift over time, but you’ll get a good few years of wear.

The next step depends on what you’ve used. I mostly use a soya milk binder—it’s natural, cheap, easy to find, and skips the rinse stage.

Rinse

If you’ve used a mordant, rinse carefully to remove any residue—use running water or swill in a bowl. After that, either dye straight away or let the fabric dry and store it for later. (If it’s dried, remember to soak it again before dyeing to help the colour go on evenly.)

 

Soya Milk Binder

Remember: soya milk is a binder, not a mordant. I mostly use this method—it’s simple, natural, and I like the way colours evolve over time. Plus, you can always re-dye later. You can even add a tannin to deepen colours.

You can make your own soya milk, but I usually buy it—just make sure it’s unsweetened and unflavoured.

  1. Pre-soak your T-shirt in warm water for at least two hours.
  2. Mix 1L soya milk with 4L water (add tannin now if using). Stir well.
  3. Add your pre-soaked T-shirt. Leave it in a cool place for 12 hours, stirring occasionally.
  4. Wring out and hang to dry—but keep the mixture!
  5. Dip the fabric again, stir for a couple of minutes, wring out and dry.
  6. Repeat the soak-and-dry process 3–4 times.
  7. After the final dry, let the fabric sit for a week before dyeing for best results.

Aluminium Lactate Mordant

This is a newer mordant—made from by-products of the sugar industry, maize and starch—which I really like. It feels like a gentler option all round: more sustainable, less harsh, and still effective.

It’s a fine powder though—so wear a mask when weighing, and gloves when needed.

Use 7–10% aluminium lactate to the weight of dry fabric. Here’s the calculation:

Weight of fabric in grams ÷ 100 × 7 = grams of aluminium lactate

  1. Pre-soak T-shirt in warm water for at least two hours.
  2. Half-fill a dye pot with hot tap water. Stir in measured aluminium lactate.
  3. Add the wet cotton, wearing gloves. Swirl gently and leave overnight.
  4. Wring out (gloves again).
  5. Rinse carefully to remove any excess mordant.
  6. Dye straight away, or dry and store.

 

What’s Next?

Next step: preparing your dye. Each plant has its own process, quirks, and colour story—and I’m adding those guides one by one. Keep checking back as the list grows—I’ll be adding more dye plant details soon.