How to Dye Cotton Yarn using Fibre Reactive Dyes - the Easy Way

Learn how to dye wool and cotton using fibre reactive dyes. 
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As much as I don't need to dye my own cotton yarn and fabrics, I had to. But dyeing cotton was scary and an entirely new process. So, a few months back, I prepped ahead for what might become a catastrophe. If you've seen my ugly yarn stash bins from years of failure, you will understand the cause for drama.

But, in the end, it wasn't so bad. Magically, I was able to streamline the process using my same system I use for wool dyeing and I want to share it with you here in preparation for my upcoming Cotton & Wool Fibre Reactive - Primary Dye Recipe Collection!

I get that it may be coming into winter where you are, so I hope that this early intervention might whisper a reminder when that warmer weather rolls around for you too. This next spring, like me, you might be tired of wearing plastic polyester tank tops in all your most dissatisfactory colours.

About Cotton & Wool Fibre Reactive Vintage Primary Collection

The vintage cotton collection is coming and it's inspired by the timeless charm of vintage hues. By using carefully measured amounts of fibre reactive dyes, we capture the warm, muted tones that evoke nostalgia and character—perfect for creating yarns with a softly aged, classic appeal. This palette encourages exploration of subtle depth, layering, and the beauty of understated colour. It’s a celebration of how gentle washes of dye can transform cotton fibre into something uniquely expressive and full of story. These curated shades invite you to experiment and create your own vintage-inspired hand-dyed wool and cotton yarns. Mix and match to make your perfect colour palette. I hope this collection inspires within you the world of hand dyeing fibre and all that is possible!

About Cotton & Wool Fibre Reactive Brights Primary Collection

Not only is this collection vintage, but by removing the third additional recipe amount,
the entire collection turns into bright airy cottony hues. 

How to dye wool using Fibre Reactive Dyes.
Based on 100g of fibre:

Your dye colour collection just got massive. You can dye wool yarn using fibre reactive dyes the exact same way as you would dye wool yarn using acid dyes and Dharma has a huge selection of colours. 

• Fibre reactive dyes are designed for cellulose fibres (cotton, linen) and form a covalent bond with the fibre. On wool, they don’t form the same bond, but they still absorb and set with heat and an acidic environment.
  
  
• Acid dyes are designed for protein fibres (wool, silk) and naturally require acidic conditions to bond, usually with heat. They form a strong, permanent bond with wool.
  

So when you use fibre reactive dyes on wool, they behave more like acid dyes, but chemically they’re still fibre reactive dyes.

Go ahead and try it! 1g of fibre reactive dye powder + 100g of wool yarn. Share your results in our Facebook group page!

How to dye cotton using Fibre Reactive Dyes.
Based on 100g of fibre:

1. Soda Ash Soak.

Dissolve 10g of soda ash for 100g yarn (in approximately 1000mls of water soak). Or, dissolve .1g of soda ash for every 1g of yarn (in approximately 10mls of water).

Add your yarn and soak for 20–30 minutes.

Remove yarn and gently squeeze out excess water — it should be damp, not dripping.

It might feel "soapy". This is normal:

• Soda ash makes the water alkaline (high pH).

• At high pH, the surface of the cotton fibre swells and changes texture.

• The solution itself feels slippery or “soapy” on your hands and on the yarn, even though there’s no soap in it. 

So the yarn isn’t actually coated with soap — it’s just the alkaline solution making it feel that way. Once rinsed and neutralized (with vinegar or thorough washing), the soapy/slippery feeling disappears.

2. Add Salt.

Then, add 500mls of warm water to your dye pot or pan. Add 10g of non-iodized salt to the water. (If dyeing colourways, divide 500 mls of water salt mixture between your colour pouring cups).

3. Prepare Your Dye Colour.

Dissolve your fibre reactive dye powder in a small amount of hot water and mix well, then add to the dye bath (warm water salt mixture). Or if dyeing colourways, add each dye powder amount to your pouring cups.

If you want to streamline the process, you can find all the Palette Parlour dye recipe collections in Muffs Shop. Fibre Reactive Cotton collection coming soon!

4. Dyeing the Yarn

• Submerge yarn in dye bath, pressing gently so it’s fully covered but not swimming freely.

• Using gloves, gently press it occasionally to ensure even colour distribution; avoid over-agitation.

• Cure in oven at 190 f / 90 C for 1 hour. Must stay wet, not dry out.

  You can mist the yarn, cover it, lay a damp towel over it, or simply leave it - my yarn never dried out in the oven (100g + 500mls liquid). But my tiny samples did and I had to cover them with a damp towel. 

• Or, cure at room temperature or warm spot (20–30°C) for 4 hours, 24 hours for dark colours. Must stay wet, not dry out.

• With confidence, rinse yarn in cold water until water runs mostly clear.

• Rinse again in warm water, condition and hang to dry.
  

About Curing Your Yarn

Fibre reactive dyes need time + warmth + alkalinity (from soda ash) to permanently bond with the cotton fibers. Unlike wool acid dyes (which bond with heat), fibre reactive dyes react slowly at room temperature, so the yarn can cure — this is called batching or curing.

Batching or Curing Conditions:

• Ideal temp: 20–30°C (68–86°F)
• Time: Minimum 4–6 hours for light colors, 6–24 hours for saturated or layered colorways
• Humidity: Yarn must stay damp, or the reaction stops. (Wrap, seal, or cover to hold moisture.)

Important Note on Dye Colour and Uptake

Fibre reactive dyes are powerful and versatile, but their results can vary depending on several factors in your dyeing process. Changing any part of the method — like water temperature, soda ash concentration, batching time, or even the type and preparation of your cotton fibre — can affect both the intensity and shade of your dyed yarn.

If you want consistent colours every time, following the method closely and maintaining stable conditions is key.

I want to share everything I know with you, so you can hone in, save time formulating, cut the confusion and enjoy the process and fibre art part of it more. Thank you to all of those who have supported Muffs development and continue to cheer me on.

~ Focus on the art part and enjoy the moment ~

Kindly, Lori from Muffs Merino

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