Oak Gall – Natural Tannin for Cellulose Fibres
Quercus infectoria G.Olivier · Whole, Cut or Ground
Oak galls, also known as oak apples, are tannin-rich growths collected from the Aleppo oak in Turkey.
Exceptionally rich in light-coloured hydrolysable tannins, oak gall is particularly useful as the first stage of a two-step mordanting process for cotton, linen, hemp and other cellulose fibres.
Oak gall generally produces a light beige base colour. It introduces slightly more colour than Tara but considerably less than many darker tannin sources, making it a useful choice when preparing cellulose for pale or delicate natural dyes.
Choose whole galls for crushing, historical processes and long-term storage, cut galls for easier extraction and straining, or ground galls for the quickest and most thorough tannin release.
At a glance
| Feature |
Details |
| Botanical source |
Quercus infectoria G.Olivier
|
| Common names |
Oak gall, Aleppo gall, Turkish gall, oak apple |
| Material |
Insect-induced growth from the oak - not an acorn or fruit |
| Origin |
Turkey |
| Forms |
Whole, cut or ground |
| Main components |
Hydrolysable tannins, principally gallotannins |
| Primary use |
First stage of cellulose mordanting |
| Other uses |
Iron-gall ink, greys and blacks with iron, historical dye processes |
| Suitable fibres |
Cotton, linen, hemp and other cellulose fibres |
| Natural colour |
Light beige |
| Colour influence |
Minimal to light warm beige |
| Material type |
Raw botanical material - not a concentrated extract |
| Solubility |
Tannins extract into water; botanical material remains insoluble |
What is an oak gall?
Oak galls are abnormal plant growths formed on the young twigs and branches of certain oak species in response to the activity of gall wasps.
The developing gall creates a protective structure around the insect larva. During its formation, the oak concentrates large quantities of tannins within the gall tissue.
The galls used for this product are collected from the Aleppo oak, Quercus infectoria, in Turkey. They are among the richest natural sources of hydrolysable tannins and have been traded for centuries for tanning, textile dyeing and ink making.
Despite the common name “oak apple,” the gall is not a fruit or acorn.
Oak gall as a tanning product
Aleppo oak galls are particularly rich in hydrolysable tannins, principally gallotannins.
Their tannin content is frequently reported at approximately 50–70%, although the precise amount varies according to the gall, maturity, collection, processing and storage.
Because oak gall contains a high proportion of comparatively pale tannins, only a relatively small quantity is required for cellulose preparation.
The resulting base colour is generally light beige. It is slightly more noticeable than Tara but remains considerably paler than many bark, fruit and leaf tannins.
Why cellulose fibres need two mordanting stages
Cotton, linen and other cellulose fibres do not naturally form a strong bond with aluminium mordants.
For this reason, our cellulose preparation uses two complementary stages:
-
A tannin treatment
-
A second mordanting treatment using alum with soda ash, aluminium acetate or aluminium lactate
The tannin stage and the aluminium stage work together. Tannin by itself does not complete the mordanting process, and the aluminium treatments are not sufficient by themselves either.
During the first stage, tannin is held by the cellulose fibre through affinity. It can still be removed if the fibre is rinsed aggressively or allowed to pass through an incomplete process.
During the second mordanting stage, the tannins are converted into insoluble tannates within the fibre. This creates the complete mordant system used to prepare the cellulose fibre for the subsequent dye.
Colour and its influence on the final shade
Oak gall produces a light beige base colour on cellulose fibres.
With pale, delicate or very clear dyes, this base colour may remain visible and gently warm the final shade.
With medium and strong dyes, its influence is usually subtle. This makes oak gall particularly useful where a high-tannin preparation is required without the stronger yellow or brown background associated with many other botanical tannins.
The final effect depends on:
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The amount of oak gall used
-
The selected form
-
Extraction time
-
The fibre and its preparation
-
The main dye colour
-
Water chemistry
-
The temperature of the tannin bath
-
The second mordanting treatment
-
Rinsing and finishing
Always prepare a sample when working towards a pale, bright or colour-sensitive result.
Choosing a form
Whole oak galls
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Suitable for historical processes, ink making and long-term storage
-
Must be crushed or broken before textile extraction
-
Require a longer soak than cut or ground material
-
Easy to store with minimal dust
-
Naturally vary in size, shape and colour
Cut oak galls
-
Offer a larger surface area than whole galls
-
Suitable for cold soaking and longer extractions
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Easier to strain than ground material
-
Produce less sediment in the tannin bath
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Can be contained inside a cloth dye bag
Ground oak galls
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Provide the greatest surface area
-
Release tannins more quickly and thoroughly
-
Best for short cold extractions
-
Produce more sediment than whole or cut material
-
Should be made into a smooth paste before being added to the bath
-
Require care to avoid creating airborne dust
The three forms are the same raw botanical material. Ground oak gall is not a concentrated extract.
How much to use
For general cellulose preparation, begin with:
10g oak gall per 100g dry fibre
Equivalent to 10% WOF - weight of dry fibre.
Whole galls must be crushed before use. Cut galls benefit from a longer cold soak, while ground galls release their tannins more readily.
Because oak gall is naturally very high in tannin, increasing the quantity is not always necessary. Excess material may deepen the beige base without improving the complete mordanting process.
These quantities are starting points. Natural tannin strength can vary between batches.
Suggested tannin treatment
-
Scour: Scour the cotton, linen or other cellulose fibre thoroughly to remove oils, waxes, sizing and processing residues.
-
Weigh: Weigh the dry fibre and calculate approximately 10% WOF oak gall.
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Prepare the material: Crush whole galls thoroughly. Cut galls may be soaked before use. Mix ground galls into a smooth paste with a small amount of water.
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Dilute: Add the prepared oak gall to enough cold water for the fibre to move freely and stir thoroughly.
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Add the fibre: Add the thoroughly wetted cellulose fibre and ensure that it is completely immersed.
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Treat: Keep the textile in a cold bath or at no more than approximately 30°C. Leave for at least 1–2 hours and up to 24 hours, moving the fibre occasionally.
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Remove: Wearing gloves, remove the fibre and gently squeeze out the excess liquid.
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Do not rinse: Tannin is held initially by affinity and can be removed by aggressive rinsing.
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Do not dry: Proceed to the second mordanting stage while the fibre remains damp.
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Second mordant: Complete the process with alum and soda ash, aluminium acetate or aluminium lactate, following the instructions for the chosen mordant.
-
Rinse: Once the second stage is complete, rinse the textile thoroughly to remove unattached mordant.
-
Dye: The textile may now be dyed immediately or dried and stored for future use.
Do not treat the oak gall bath as a complete mordanting process by itself. The second mordanting stage is essential.
Dyeing cotton, linen or another cellulose fibre? Find our complete cellulose mordanting guide here.
Choosing the second mordant
After the oak gall treatment, complete the mordanting process with one of the following:
Alum with soda ash
Our traditional two-stage method uses 12% WOF alum and 1.5% WOF soda ash after the tannin treatment.
The alum and soda ash solutions are prepared separately and then combined before the damp, tannin-treated textile is added.
Leave the textile in the second bath for a minimum of two hours and up to 24 hours. Rinse thoroughly after this stage.
Aluminium acetate
Aluminium acetate can be used as the second mordanting stage after the oak gall treatment.
Follow the appropriate quantity and method for the particular aluminium acetate product. A chalk afterbath may be required where specified by the recipe.
Aluminium lactate
Aluminium lactate is another option for the second stage of suitably prepared cellulose fibres.
Apply it after the oak gall treatment, following the correct quantities and safety guidance for the product.
Do not combine quantities or instructions from unrelated mordanting methods.
Tips from the dye pot
| Tip |
Details |
| Scour thoroughly |
Oils, waxes and sizing can prevent even tannin and mordant uptake. |
| Keep the bath cool |
Heat can oxidise tannins and produce a darker base colour. |
| Crush whole galls |
Whole galls must be broken to expose their tannin-rich interior. |
| Allow cut galls time |
Cut material benefits from a longer soak than ground oak gall. |
| Make ground gall into a paste |
Mixing it with a little water first helps prevent dry lumps and floating powder. |
| Do not rinse between stages |
Aggressive rinsing can remove tannin before it has been converted into an insoluble tannate. |
| Do not allow the fibre to dry |
Proceed directly from the tannin treatment to the second mordanting stage. |
| Complete both stages |
Neither oak gall alone nor the aluminium treatment alone completes this cellulose mordanting system. |
| Save the tannin bath |
The bath may retain useful tannin and can be saved for another treatment. |
| Consider the base colour |
Oak gall introduces a light beige background that may influence very pale colours. |
| Keep records |
Note the form, WOF, temperature, duration, mordant and dye used. |
Using oak gall with iron
Oak gall reacts strongly with iron to produce grey, blue-grey, charcoal and black.
For a grey or black textile process, the tannin-treated fibre can be moved into a carefully measured iron bath without completing the alum stage. This is a different process from preparing cellulose for bright natural dye colours.
If iron is used as a modifier, begin with a very small quantity. Excessive iron can make colours harsh and may damage fibres over time.
The reaction between oak gall tannins and iron is also the basis of traditional iron-gall ink.
Iron-gall ink
Oak galls have been used for centuries in the preparation of iron-gall inks.
A concentrated oak gall extraction is combined with an iron salt, traditionally ferrous sulphate, to produce a dark iron-tannate colour. Gum arabic may then be added as a binder and to adjust the flow of the ink.
Iron-gall ink can be acidic or corrosive if poorly formulated. Use a researched recipe, measure all ingredients accurately and test the finished ink before applying it to valuable paper, textiles or artwork.
Tannin performance
Oak gall is used primarily to support the mordanting and subsequent dyeing of cellulose fibres rather than as a strong standalone dye.
The effectiveness of the complete preparation depends on:
-
Thorough scouring
-
Correct preparation of the chosen oak gall form
-
Even tannin application
-
Keeping the tannin bath cool
-
Avoiding rinsing and drying between stages
-
Completion of the second mordanting stage
-
The chosen aluminium mordant
-
The dye and dyeing method
-
Water chemistry
-
Rinsing, washing and aftercare
Oak gall’s light beige colour may remain visible beneath very pale dyes. With medium and deep colours, it generally provides a comparatively neutral tannin base.
Natural variation
Oak galls are insect-induced natural growths and vary considerably in size, form, colour and surface texture.
Whole galls may have natural holes where the mature gall wasp emerged. They may also contain small quantities of woody material or natural insect residue.
Colour can range from pale beige and grey-green to olive, brown or almost black. These differences are normal and do not necessarily indicate the strength of the tannin.
Particle size in cut and ground material may vary between batches. Tannin strength is also affected by maturity, harvesting, storage and processing.
Always sample before beginning an important or colour-sensitive project.
Storage and safe handling
-
Store sealed in a cool, dry place away from direct sunlight.
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For textile dyeing, tanning, ink making, paper and craft use only.
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Not for consumption or use in food, drinks, cosmetics or herbal preparations.
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Avoid creating or breathing dust, particularly when handling ground oak gall.
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Work in a well-ventilated area.
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Wear suitable respiratory and eye protection when dusty material may become airborne.
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Avoid contact with the eyes, mouth and open wounds.
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Wear gloves where appropriate.
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Follow the safety instructions for alum, soda ash, aluminium acetate, aluminium lactate, iron salts and every other auxiliary used.
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Use dedicated dyeing and ink-making utensils—never food-preparation equipment.
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Keep away from food and out of reach of children and pets.
What you receive
Your chosen net weight of Turkish Aleppo oak galls in whole, cut or ground form, supplied in a sealed pouch.
Alum, soda ash, aluminium acetate, aluminium lactate, iron salts, dyes and other mordanting materials are sold separately.
Display jars, dyed textiles, inks and photographic props are not included.
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