ALUM MORDANT (Potassium Aluminum Sulphate Dodecahydrate)
~ Necessary for most plant dyes to ensure colour fastness ~

Alum is considered the safest and least harmful mordant used in natural dyeing. It helps fix dyes to fibres and enhances colour retention. What many don't realise is that Alum occurs naturally in nature, and some plants, such as Lycopodium, contain natural Alum.

Mordanting Cellulose Fibres

For mordanting cellulose fibres, please refer to our blog for detailed recipes:

• How to Mordant Linen and Cotton Fabrics Successfully – AppleOak FibreWorks

• How to Mordant Linen and Cotton Successfully Without Tannins – AppleOak FibreWorks

Basic Recipe for Wool

Ingredients:

• 10%-20% Alum (based on the Dry Weight of Fibre - D.W.F.)

• Wool (or other protein fibres)

• Water

• Optional: 5% Cream of Tartar (for hot mordanting)

Instructions:

Cold Mordanting:

1. Weigh your dry textile material.

2. Soak the dry material in water.

3. Dissolve Alum in hot water and add to a mordanting pot filled with water.

4. Add pre-soaked wool and let sit for 24-72 hours.

Hot Mordanting:

1. Dissolve Alum in hot water and add to a mordanting pot filled with water.

2. Add 5% Cream of Tartar to slow down the mordant uptake.

3. Add wool and bring to 80°C for 1 hour.

4. Let cool, then rinse and dye or dry for later use.

Alum is ideal for protein fibres like wool and silk, ensuring vibrant and lasting colour results.

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IRON MORDANT ~ Mordant, Colour Changer, increased light fastness

Iron (Ferrous Sulfate) is used alone as a mordant, influencing Colours and to increase light fastness when used in combination with other natural dyes.

Iron is best known for shifting yellows into greens, keep in mind that this is not given and doesn't work with every yellow plant dye, in which case it will be more of a brown. it is used to increase light fastness for weaker plant dyes, bu it will always sadden and/or darken the colours. 

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Basic recipe:

When adding Iron to your dye bath start of with 3% and use it at the end of your dye bath or as an after bath. Allow to oxidize for 10 min for full colour development.

*If you like your colours darker, increase the Iron amount by 1-2% at a time. 

**Leave for 10min than remove from dye bath - Iron will make wool brittle.

POTASH – pH ADJUSTER & SCOURING AGENT

Chemical name: Potassium Carbonate (K₂CO₃) | Grade: Textile | Use rate: 3–10%

No natural-dye studio is complete without potash (Pottasche in German). This alkaline powder (K₂CO₃) is slightly stronger than soda ash and is traditionally used to raise the pH of dye baths and indigo vats, scour cellulose fibres, and intensify plant yellows such as weld by increasing alkalinity.

💡 Note: This product was previously listed as Soda Ash (Sodium Carbonate). We have updated the listing to Potash (Potassium Carbonate) to reflect the correct material.

Uses

• Boost pH in indigo, woad, or fructose vats
• Add to your scouring bath
• Intensify weld yellow and other plant yellows
• Balance acidic dye baths when needed

In a nutshell

• Material: Potash (Potassium Carbonate K₂CO₃)
• Function: pH enhancer & cellulose scour
• Dose: 30–100 g · L⁻¹ (3–10% owf) dissolved in hot water or dye liquor
• Compatibility: All natural dyes; indigo & woad vats
• Packaging: Resealable moisture-proof pouch
• Safety: Wear gloves & mask; store cool, dry, and away from acids

Basic directions

Dissolve the required potash in hot water (or directly into a hot dye bath) at 3–10%. Stir until clear, then add to the dye pot or fibre scour. For indigo vats, add potash after the pigment to adjust alkalinity before introducing a reducer.

Safety & storage

Potash is strongly alkaline. Avoid inhaling dust and protect eyes and skin. Store sealed and dry; keep away from children and acids. Dispose of effluent according to local regulations.

💡 Tip: Pair potash with our Natural Indigo Powder or Indigo Kits for a complete dye setup.

Potash vs Soda Ash Table

HYDROS – REDUCING AGENT FOR INDIGO / WOAD VATS
Chemical name: Sodium Dithionite (Thiox) | Grade: Textile | Use rate: ≤ 25 g per 10 L vat

Hydros—also known as sodium dithionite, thiox, or hydrosulfite sodium—is the fast, reliable oxygen remover used to bring indigo or woad vats into reduction. A quick sprinkle over the surface turns the liquor a yellow-green and readies it for dipping within about an hour. However, for best performance leave the vat for 2 days before dyeing.

Why choose our Hydros
• Consistent, high-purity powder for rapid vat activation
• Cost-effective alternative to spectralite (use a little more, save a lot)
• Fine, free-flowing granules supplied in a resealable pouch

Directions (10 L vat)

1. Set vat at 40 °C with indigo/woad and alkali already dissolved.

2. Sprinkle 25 g Hydros evenly over the surface. Always add Hydros to water—never water to Hydros.

3. Cover and wait ± 60 min. Vat should shift to yellow-green with a metallic film.

4. Stir gently, keeping air out, then begin dipping.

In a nutshell
• Function: Oxygen remover / vat reducer
• Other names: Sodium dithionite, thiourea dioxide, thiox, hydrosulfite sodium
• Compatibility: Indigo, woad, other vat dyes
• Typical dose: 2–5 g · L⁻¹ (max. 50g per 10 L)
• Packaging: Resealable moisture-proof pouch
• Safety: Wear gloves & mask; store cool & dry away from acids and oxidisers

Safety & storage
Keep sealed, cool and dry. Avoid inhalation of dust. Add powder to water—never the reverse—to prevent rapid exothermic reaction. Dispose of spent vats according to local regulations and keep away from children.

Need a full setup? Pair with our Natural Indigo Kit for a ready-to-dye bundle.

It is possible to create a vat from indigo, lime (calcium hydroxide) and over-ripe fruit such as bananas or dates that relies on the chemistry of the sugars* rather than fermentation of the fruit. But it’s easier to simply use fructose shared in

Michel Garcia’s 1-2-3 recipe. It’s very simple: One Part indigo, two parts lime and three parts fructose, plus warmth.

*Fructose and glucose found in ripe fruit are reducing sugars; ordinary sugar – sucrose – is not a reducing sugar. 

TARA POWDER ~  is a natural tanning product

Grown in the mountains of Peru.

Tara powder will stain the fibres grey and it is recommended to use a strong dye so the colour isn't too influenced. I am using it for plant dyed flax fibres and LinCot yarns and found, that it actually adds some more depth to the colour.

Basic Recipe:

Please see our blog post on How to mordant linen and cotton fabrics successfully – AppleOak FibreWorks

GUAR GUM ORGANIC
Use: Printing with Natural Dyes | Botanical Name: Cyamopsis tetragonoloba | Alternative to: Gum Arabic | Alternative Name: Guaran

Guar Gum is derived from organic guar beans and is an essential ingredient in natural dye printmaking. It is used to create a paste that works effectively with mordant dyes , allowing for precise application. Guar Gum thickens as it absorbs liquid, making it ideal for printmaking on textiles. Use a handheld blender or mixer to ensure even dissolution, and adjust the amount as needed for the desired consistency.

Key Features:

• 100% Organic Guar Gum
• Alternative to Gum Arabic
• Used for printing with mordant dyes & Indigo
• Thickens naturally for better application
• Helps create a mordant carrier for cellulose fabrics
• Best mixed with a handheld blender for smooth consistency

Function:
Guar Gum acts as a mordant carrier in natural dyeing. When combined with mordant-based dyes, it forms a rubber-like substance that can be drawn or printed onto fabric. Once dried, the gum must be removed with a Chalk and Wheat Bran solution, followed by a rinse. The fabric is then ready for dyeing. After dyeing, rinse thoroughly and boil with a small amount of organic washing-up liquid.

Basic Recipe for Guar Gum Mordant Carrier (for Cellulose Fabrics):

Ingredients for 100g:

• 10g Alum
• 5g Soda Ash
• 84g Vinegar (5% Acetic Acid)
• 1g Guar Gum

Storage & Usage:

• Once mixed, the solution will only last a couple of days.
• Store in the fridge and use fresh for best results.

Enhance your textile printing with this essential natural thickener, perfect for artists and dyeing enthusiasts.

Sodium Acetate ~ Used to turn Ferrous Sulfate into Ferrous Acetate; used in the Mordanting Recipe for Cotton and Linen without Tannin (see below)

Sodium acetate, NaCH₃COO, also abbreviated NaOAc, is the sodium salt of acetic acid. We use Sodium Acetate to turn Iron into an easier digestible version of itself, Iron acetate. Similar to 'Iron Water' but you can control the amounts. Iron acetate is not as harsh on the fibres and can be easier digested by nature or your septic tank when turned into rust. Once made, it has no shelf life and needs to be used immediately. 

For mordanting Cellulose fibres, please choose one of the following recipes on our blog:

How to mordant linen and cotton fabrics successfully – AppleOak FibreWorks

How to mordant Linen and Cotton successfully without Tannins – AppleOak FibreWorks

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Basic recipe: 

1part Ferrous Sulfate

1part Sodium Acetate

Mix and dissolve in Water. I find that it makes the iron stronger and we only use 1% of Iron acetate on most recipes. Warm water will also intensify the reaction.

CREAM OF TARTAR ~ To change colour (PH indicator) and soften fibre

Cream of Tartar, also known as potassium bitartrate, is produced by fermenting grape juice. It is used to acidify the dye bath to effect a colour change, and in mordanting to soften wool fibers as well as slowing down the mordant uptake in a hot mordant bath.

Instructions:

In general Cream of tartar can be dissolved in the dye bath. It helps to lower the PH of the bath.
PH of Cream of tartar is 5.

MYROBALAN CHEBULIC ~ a tannin used for (pre) mordanting cellulose (Cotton, Linen) Fibres. Recipe below.

ORIGN: India

Myrobalan is a very common tannin used in India and around Asia. It creates a plum-like fruit from various trees of the genus Terminalia, formerly used in medicine as a mild laxative and now used in the dyeing industry.

Myrobalan creates butter yellow on fabric, like most tannins. Tannin is important for mordanting cellulose fibres like cotton and linen. Alum alone is not a suitable mordant for cellulose fibres and its use will produce inferior colours.

Myrobalan can be used in print, over dye with indigo for teal, use as a stand alone colour or as a mordant.

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Recipe Downloadable PDF for creating Greys and Charcoal 

Basic recipe for mordanting cellulose fibres:

A 2 step process, please read through the entire instructions first.

Step 1:

Ingredients:

10% Myrobalan (10% of the weight of fabric (w.o.f.))


1.Fill a plastic or stainless steel vessel with hot water (40-50 d. Celsius/100-120F) to a 30:1 ratio (water : fabric)

2. add tannin and stir until dissolved or evenly distributed

3. add fabric, immerse fully for 1-2 hours. The bath will cool down, which is totally fine. Stir occasionally.

4. use rubber gloves when removing fabric, squeeze fabric. Rinse very lightly or better spin it out using a centrifugal spinner or washing machine. Tannin is bound to the fibre only by affinity and can be removed if rinsed aggressively.

5. save mordant for future use.

6. don't let it dry before moving to the 2nd mordanting step.

Step 2:

Ingredients:
Alum 12% (w.o.f.) Dissolved in enough boiling water, cool.
Soda Ash 1.5% (w.o.f.) Dissolve in enough boiling water, cool.

1. Combine the two solutions while stirring. It will bubble, so make sure your vessel is big enough.

2. Bubbles will subside quickly and you should be left with a clear liquid. Add additional hot water as described above. Follow steps 3 - 5 from above.

3. Rinse the textile well, to make sure any unattached mordant is rinsed off.

4. The textile may be dyed immediately or dried for future use.


Tips:

*Too hot and the tannin will oxidize, which is fine, if you want a potentially darker colour. For overdyeing, it is best to keep the colour as light as possible.
** You can also use cold water instead of hot, but it will require a 12h soak at least.
***Any tannin can be used with this recipe, but for lighter results use Oak Gall or Tara.

Enjoy!

Join The Natural Dyers & Growers Academy to share your experiences and get support from fellow growers.

SODA ASH – pH ADJUSTER & SCOURING AGENT

Chemical name: Sodium Carbonate (Na₂CO₃) | Grade: Textile | Use rate: 3–10%

No natural-dye studio is complete without soda ash (Soda in German). This alkaline powder (Na₂CO₃) raises the pH of dye baths and indigo vats, scours cellulose fibres such as cotton and linen, and brightens plant yellows like weld by increasing alkalinity.

💡 Note: Soda ash is milder than Potash (Potassium Carbonate), making it suitable for situations where a gentler pH adjustment is preferred. If you bought our 'Soda Ash' in the past, you would be looking for Potash, rather than this new Soda Ash listing.

Uses

• Boost pH in indigo, woad, or fructose vats
• Scour cotton, linen, hemp, and bamboo before mordanting
• Intensify weld yellow and other plant yellows
• Balance acidic dye baths when needed

In a nutshell

• Material: Sodium carbonate (soda ash, Na₂CO₃)
• Function: pH enhancer & cellulose scour
• Dose: 30–100 g · L⁻¹ (3–10% owf) dissolved in hot water or dye liquor
• Compatibility: All natural dyes; indigo & woad vats
• Packaging: Resealable moisture-proof pouch
• Safety: Wear gloves & mask; store cool, dry, and away from acids

Basic directions

Dissolve the required soda ash in hot water (or directly into a hot dye bath) at 3–10%. Stir until clear, then add to the dye pot or fibre scour. For indigo vats, add soda ash after the pigment to adjust alkalinity before introducing a reducer.

Safety & storage

Soda ash is strongly alkaline. Avoid inhaling dust and protect eyes and skin. Store sealed and dry; keep away from children and acids. Dispose of effluent according to local regulations.

💡 Tip: If you need a stronger pH adjuster, try our Potash (Potassium Carbonate K₂CO₃).

Potash vs Soda Ash Table

A small amount of Citric Acid can make a big difference in adjusting the PH levels of various substances. It falls between lemon juice and Tartaric Acid in terms of strength and is a valuable tool in achieving desired levels of acidity in natural Dyeing.

Tartaric Acid, a byproduct of wine making, is a stronger alternative to Citric Acid. It is commonly used in natural dyeing to lower the pH to 1+ and intensify and brighten cochineal reds. Additionally, it serves as an antioxidant (E334) and is naturally present in grapes and bananas.

A Modern Mordant for Linen, Hemp & Cotton

Aluminium acetate is one of the most widely used mordants for natural dyeing on cellulose fibres such as linen, hemp, cotton, ramie and nettle.

Unlike alum, which works exceptionally well on protein fibres, aluminium acetate has become a popular choice for cellulose fibres because it can help produce bright, clear and colourfast shades.

Product Details

Our Approach to Mordanting Cellulose Fibres

At AppleOak FibreWorks, we use two different approaches depending on the desired result.

For Maximum Colourfastness

A tannin followed by aluminium mordant remains one of the most reliable methods for achieving durable colour on cellulose fibres.

Recommended tannins include:

• Oak Gallnut
• Sumach Gallnut
• Tara Powder

These tannins contribute very little background colour while helping create a strong bond between fibre, mordant and dye.

For projects where a slight warm tone is acceptable, the following tannins may also be used:

• Acacia Extract
• Myrobalan
• Chestnut Extract

For the Whitest Possible Background

When preserving the natural whiteness of linen or cotton is important, we recommend a tannin-free aluminium acetate method similar to the approach described in our guide:

How to Mordant Linen and Cotton Successfully Without Tannins

In this method, aluminium acetate is not used directly as a purchased mordant. Instead, a strong aluminium acetate concentrate is prepared from alum (potassium aluminium sulphate) and sodium acetate before use.

1. Scour the fibre thoroughly.
2. Prepare a concentrated aluminium acetate solution from alum and sodium acetate according to the recipe in our guide.
3. Mordant the fibre using the freshly prepared aluminium acetate solution.
4. Follow with a chalk bath (calcium carbonate) to fix excess acetate and improve mordant performance.
5. Rinse and proceed to dyeing.

This approach avoids the cream, beige or yellow cast that even low-colour tannins can introduce, making it particularly useful when dyeing pale yellows, pinks, blues and other delicate shades where a white background is desirable. However, it works best on smaller projects.

A Note on Tannins and Background Colour

Tannins can improve dye uptake and durability on cellulose fibres, but they also contribute varying degrees of colour to the fibre.

If maintaining a bright white base is the priority, a tannin-free aluminium acetate and chalk process is often the better choice.

Suggested Usage Rates

Mordanting Guides & AppleOak Methods

Detailed cellulose mordanting guides can be found here:

https://appleoakfibreworks.com/blogs/news/tagged/how-to-mordant-linen

Including:

• Tannin mordanting methods
• Tannin-free cellulose mordanting
• Aluminium acetate and chalk methods
• Approaches for preserving a white background

Join Our Free Natural Dyeing Community

Looking to deepen your natural dyeing knowledge and connect with other passionate dyers?

Start by joining our free Natural Dyers Academy community, where you'll find inspiration, discussions, resources, and opportunities to learn more about natural dyes, mordanting, fibre preparation, colour exploration, dye plant cultivation, and sustainable textile practices.

Join the free community here:

https://the-natural-dyers-academy.mn.co/share/Mz7coMI6VgbJMchB?utm_source=manual

Inside the community you'll find:

• Natural dyeing discussions and inspiration
• Helpful resources and learning opportunities
• Dye plant growing and harvesting tips
• Colour studies and recipe sharing
• Community support from fellow natural dyers
• Information about workshops, courses, and Academy membership options

If you'd like more structured learning, in-depth tutorials, workshops, and exclusive resources, you can also explore our full Natural Dyers Academy membership from within the community.

Please Note

For textile and craft use only.

Not intended for food, cosmetic or medicinal applications.

A Modern Aluminium Mordant for Linen, Hemp & Cotton

Aluminium lactate is a highly effective mordant for natural dyeing on cellulose fibres such as linen, hemp, cotton, ramie and nettle.

Produced from lactic acid obtained through the fermentation of renewable raw materials, it offers a more sustainable alternative to aluminium acetate while producing bright, clear and colourfast results.

Fully soluble at room temperature and compliant with GOTS 6.0 standards, aluminium lactate is easy to use and suitable for both beginners and experienced natural dyers.

Product Details

Our Approach to Mordanting Cellulose Fibres

At AppleOak FibreWorks, we recommend a tannin-first approach when mordanting cellulose fibres.

Unlike wool and silk, cellulose fibres have relatively few natural binding sites for mordants. While aluminium mordants can improve dye uptake on their own, we have consistently found that a preliminary tannin treatment produces stronger and more durable results.

The tannin acts as a bridge between the fibre, the aluminium mordant and the dye, helping improve colour depth, wash fastness and long-term durability.

Step 1 – Tannin Bath

Low-colour tannins:

• Oak Gallnut
• Sumach Gallnut
• Tara Powder

For a background colour:

• Acacia Extract
• Myrobalan
• Chestnut Extract

Step 2 – Aluminium Lactate Bath

Use aluminium lactate at approximately 5–8% WOF (weight of fibre).

A Note on Dunging & Chalk Baths

Some modern recipes recommend aluminium mordants followed by bran, chalk or dunging baths.

While these methods may improve dye uptake, our own experience and understanding of the chemistry suggest they do not create the same durable tannin–aluminium complex traditionally used on cellulose fibres.

For projects where wash fastness matters, we continue to recommend tannin followed by aluminium mordanting.

Suggested Usage Rates

Traditional Recipes, AppleOak Methods & Learning Resources

Natural dyeing is full of conflicting recipes and advice. Over the years we have tested a wide range of mordanting methods on linen, hemp and cotton and shared our findings through both our blog and the AppleOak Academy.

Traditional recipes, AppleOak cellulose mordant guides and in-depth educational resources can be found here:

AppleOak Blog

https://appleoakfibreworks.com/blogs/news/tagged/how-to-mordant-linen

Join Our Free Natural Dyeing Community

Looking to deepen your natural dyeing knowledge and connect with other passionate dyers?

Start by joining our free Natural Dyers Academy community, where you'll find inspiration, discussions, resources, and opportunities to learn more about natural dyes, mordanting, fibre preparation, colour exploration, dye plant cultivation, and sustainable textile practices.

Join the free community here:

https://the-natural-dyers-academy.mn.co/share/Mz7coMI6VgbJMchB?utm_source=manual

Inside the community you'll find:

• Natural dyeing discussions and inspiration
• Helpful resources and learning opportunities
• Dye plant growing and harvesting tips
• Colour studies and recipe sharing
• Community support from fellow natural dyers
• Information about workshops, courses, and Academy membership options

If you'd like more structured learning, in-depth tutorials, workshops, and exclusive resources, you can also explore our full Natural Dyers Academy membership from within the community.

Please Note

For textile and craft use only.

Not intended for food, cosmetic or medicinal applications.