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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OAK GALL
Use: Cellulose Fibre Mordant | Harvested From: Aleppo Oak in Turkey | Also Known As: Oak Apple | Recipe: link below

Oak Gall, also known as Oak Apple, is harvested from the Aleppo Oak in Turkey and is a traditional mordant used for cellulose fibres. Due to its high tannin content, it is an effective mordant for preparing cellulose-based fabrics for natural dyeing. Unlike other tannin-based mordants, Oak Gall only stains the cellulose fibre a light beige, making it a preferred choice for delicate dyeing projects.

Key Features:

• High tannin content for cellulose mordanting
• Minimal staining cellulose fibres
• Available whole, cut, or ground

Function:
Oak Gall is used to prepare cellulose fibres for natural dyeing, helping the dye adhere to the fabric without leaving stains. Its high tannin content ensures vibrant and durable colours on cellulose fabrics like cotton, linen, and hemp. 

Storage & Usage:

• Available in whole, cut, or ground form.
• Store in a cool, dry place.

Perfect for natural dyers and textile artists working with cellulose fibre. Please see this recipe for mordanting cellulose with Gallotannin

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

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.

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.

Lime (calcium hydroxide) 

It is possible to create a vat from indigo, lime (calcium hydroxide) and over-ripe fruit such as dates or bananas, relying on the chemistry of the sugars* rather than fermentation of the fruit. But it’s easier to simply use fructose. It’s very simple: One Part indigo, two parts lime and three parts fructose, plus warmth.

You can either purchase your individual items or you can purchase our Organic Indigo Vat Kit. The Organic Indigo Recipe is also available as a download and so is an Organic indigo Vat Troubleshooter (comes with a free download link if you purchase the Organic Indigo Vat Kit. 

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