An Essential Ingredient for Indigo Dyeing

Hydrated lime, also known as calcium hydroxide, is a traditional material widely used in indigo dyeing and indigo production.

Produced by reacting lime derived from limestone with water, hydrated lime is a naturally occurring alkaline material with a long history of use in indigo processing, agriculture, building and water treatment.

Hydrated lime is commonly used in indigo reduction vats, including iron-lime vats and organic fructose vats, and plays an important role in traditional indigo extraction and production methods.

Product Details

Uses in Indigo Dyeing & Production

Hydrated lime is commonly used for:

• Iron-lime indigo vats
• Organic fructose indigo vats
• 1-2-3 and 1-3-2 indigo vat recipes
• Lime water preparation
• Indigo extraction and precipitation
• Shade enhancement before indigo dyeing
• Traditional indigo production methods

Lime Water for Indigo Extraction

Hydrated lime is often used to prepare lime water, an alkaline solution used during the extraction and precipitation of indigo pigment from indigo-bearing plants.

Lime water helps adjust pH during extraction and is an important component in many traditional indigo production methods.

Many dyers and indigo producers keep a supply of lime water on hand for both pigment extraction and indigo vat preparation.

Organic Indigo Vats

Many dyers use lime alongside fructose to create a simple and effective organic indigo vat.

A common recipe follows:

1 Part Indigo : 2 Parts Lime : 3 Parts Fructose

Combined with warmth, this creates a reduction vat based on sugar chemistry rather than fermentation.

Understanding Lime & Carbonation

Hydrated lime is produced from calcium carbonate (limestone).

When exposed to air, it slowly reacts with carbon dioxide and gradually converts back into calcium carbonate through a natural process known as carbonation.

For dyers, this means:

• Fresh lime is generally more active and predictable.
• Long-term exposure to air reduces effectiveness.
• Moisture accelerates deterioration.
• Proper storage helps maintain performance.

Storage Recommendations

• Keep tightly sealed when not in use.
• Store in a cool, dry place.
• Avoid prolonged exposure to air.
• Always use clean, dry utensils.

Stored correctly, hydrated lime remains usable for a long period, although freshness is always preferred for indigo vat preparation and indigo extraction work.

Learn More About Indigo Vats

Hydrated lime is used extensively throughout our Indigo Week resources and AppleOak indigo guides.

You can explore our indigo articles and tutorials here:

https://appleoakfibreworks.com/blogs/news

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.

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Please Note

For textile, craft and technical use only.

Not intended for food, cosmetic or medicinal applications.

Traditional Chalk for Cellulose Mordanting & Natural Dyeing

Calcium carbonate, commonly known as chalk, has long been used in natural dyeing and textile preparation. It is particularly valued in traditional cellulose mordanting, where it is used during the dunging process to help stabilise aluminium acetate and prepare fibres for dyeing.

At AppleOak FibreWorks, we offer two sources of calcium carbonate:

Blanc de Meudon (France)

A traditional, finely milled chalk widely used in textile work, natural dyeing and decorative applications.

Burren Limestone Chalk (Co. Clare, Ireland)

Collected from limestone sourced near the Burren, one of Ireland's most iconic limestone landscapes. Rich in naturally occurring calcium carbonate, this minimally processed chalk performs beautifully for dunging and textile work.

As it is collected in its natural state, occasional small stones or mineral particles may be present. If required, simply sieve before use.

Product Details

Uses in Natural Dyeing

Calcium carbonate is commonly used for:

• Dunging after aluminium acetate mordanting
• Traditional cellulose mordanting processes
• Stabilising aluminium acetate within fibres
• Madder dye baths where water contains insufficient calcium
• Pigment and colour preparation
• pH adjustment in selected dye processes

Historically, dunging often involved cow dung. Today, calcium carbonate provides a cleaner and more practical alternative while serving a similar purpose in many mordanting systems.

Suggested Usage

Dunging Bath

• 1–2 teaspoons per litre of water
• or approximately 1% WOF (weight of fibre)
• or 1–3g per litre

Stir thoroughly before use, if you are using Burren stone, double the quantity.

Calcium & Madder

Calcium plays an important role in many madder dye baths.

Where local water is naturally soft and low in calcium, adding calcium carbonate can help encourage brighter, clearer red shades.

Choosing Between Our Two Options

Both products perform well in natural dyeing applications.

Choose Blanc de Meudon if:

• you prefer a traditional textile-grade chalk
• you want a consistently fine texture

Choose Burren Limestone if:

• you value locally sourced materials
• you enjoy working with minimally processed natural materials
• you appreciate a connection to place and landscape

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

The Burren Limestone Chalk is a natural material and may contain occasional small stones or mineral particles. Sieving before use is recommended if a finer texture is required.

For textile, craft and technical use only.

Not intended for food, cosmetic or medicinal applications.