Oak Gall Extract
OAK GALL EXTRACT
A rich source of natural tannins
Oak galls are round growths that form on the branches of oak trees when wasps lay their eggs beneath the bark. Galls are one the richest sources of natural tannins, and for centuries they have been used for tanning leather, making ink, and treating cotton before mordanting and dyeing. Shepherd Textiles Oak Gall Extract is a rustic oak gall extract made in India from galls harvested from Aleppo Oak trees. It retains the full spectrum of natural tannins found in oak galls, including dark tannins that can be used to dye cotton or linen a soft brown shade. It makes an excellent base for mordanting and then dyeing plant fibers with other colors, especially in combination with an iron mordant. Use at 10% weight-of-fabric to dye or to tan cotton or linen fibers. Product of India.
1. Background on Oak Galls
Galls are abnormal tannin-rich growths that form on a variety of plants in response to attacks by insects like wasps and aphids. Galls can be found on maples, elm trees, rose bushes, and even sage brush, but the most abundant and useful galls for dyers are the ones harvested from sumacs and oak trees. Indeed, galls are such a common feature on some oak species that the Aleppo oak — native to the eastern Mediterranean region from Greece to Syria — was given the Latin name quercus infectoria, which translates as something along the lines of “dyer’s oak” (the Latin root, inficere, has the sense of “to dye” or “to stain” and in English later came to mean “being infected by a foreign body,” making the Linnaean taxonomy doubly appropriate in this case). The galls found on Aleppo oaks are generally spherical protuberances that form on branches when gall wasps lay their eggs inside the bark. The galls provide a safe space for the larvae to grow until they are old enough to emerge and fly away.
Oak galls have been harvested for thousands of years for dyeing and medicinal purposes; there are papyri from the 3rd and 4th centuries C.E. attesting to the use of gall baths for treating wool. However, in contemporary dyeing oak galls are used primarily as a treatment for plant fibers like cotton and linen. Plant-based fibers have little natural attraction for metal mordants like aluminum and iron, but the fibers will readily absorb enormous quantities of soluble tannins. Once saturated with tannins, a step known as tanning or engallage, the plant fibers can successfully be mordanted because the tannins themselves will form the necessary bond with the metals. After tanning and mordanting, the plant fibers can be dyed a variety of rich shades from bright yellows to deep blacks.
Shepherd Textiles sells two varieties of oak gall extract intended for dyeing textiles. Our standard Oak Gall Extract is a rustic, full-spectrum extract made in India from Aleppo oak galls. It contains the full spectrum of natural tannins found in oak galls, including lighter gallic tannins and darker ellagic tannins. When applied to cotton or linen it will dye the fiber a soft brown shade, and it can be used on its own as a completely natural brown dye or it can be used as the base for mordanting plant fibers and then dyeing them with other colors. Because it imparts a brownish tint to the fiber, we find that it works especially well with an iron mordant (which further darkens the color) and as a base for dyeing dark shades like gray, brown, and black. Oak Gall Light Extract is a more refined extract of Aleppo oak galls that is produced in France. It contains mostly clear gallic tannins, and imparts only the tiniest hint of color when applied to cotton or linen. Although not much use as a dye itself, it makes an excellent base for subsequently mordanting with aluminum or iron and then dying bright shades of yellow, crimson, purple, or black. Use either extract at 10% weight-of-fabric to prepare cotton or linen for mordanting.
2. Safety Precautions
This product is intended for textile projects only. Do not ingest or apply directly to skin or hair.
Avoid eye contact. If eye contact occurs, rinse with cool water.
Open carefully to avoid spills. If a spill occurs, quickly wipe up with a paper towel or rag.
Oak Gall Extract can permanently dye clothing, countertops, rugs, utensils, or other property, especially in combination with iron. Avoid contact with anything that is not meant to be dyed.
Use only dye pots and utensils dedicated to dyeing. Do not use any pots, containers, spoons, tongs, thermometers, or other utensils that will be used for food preparation..
Oak Gall Extract, metal mordants, and all dye baths and mordant liquors made while dyeing, should be kept out of reach of children and pets. Use only with adult supervision.
Shepherd Textiles, LLC is not liable for any misuse of this product or any unintended staining of your clothing, workspace, or other property. Use only as directed.
3. Recommended Supplies
Candy thermometer. A cheap candy thermometer that clips to the side of the dye pot will make it easier to track the temperature.
Iron mordant. The form of iron used as a mordant with Oak Gall Extract is ferrous sulfate (sometimes labeled ferrous sulfate heptahydrate).
Tea bags or a coffee filter. For straining the dye bath.
Scale. Use a scale to weigh out fiber, mordant, and Oak Gall Extract.
Dye pot. Use a dye pot large enough to hold all your fibers, with plenty of room for them to move around and for the liquid to circulate freely. A stainless steel stock pot usually works well.
Metal tongs. A pair of tongs is useful for stirring and taking fabric out. Use tongs dedicated to dyeing, and not for food preparation.
Rubber gloves. Wear rubber gloves while handling mordanted/dyed fiber before it is rinsed.
Recipes
4. Beige on Cotton/Linen
Oak Gall Extract is a rich source of natural tannins, which plant fibers like cotton and linen will absorb in large quantities. As a result, there is no need to pre-mordant plant fibers in order to dye them with Oak Gall Extract (although they should be cleaned and scoured very well before beginning!). On its own, Oak Gall Extract will give plant fibers a soft and natural gray-brown shade. However, this is also the base recipe for further modifications, such as mordanting and dyeing with other colors. If you plan to stop here, using it only for the soft sandstone shade, you can thoroughly rinse the fibers at the end of the recipe. However, if you plan to proceed to mordanting and dyeing with other colors, the fibers should be wrung out but not rinsed.
Cotton shirt, 5% WOF
Cotton broadcloth, 5% WOF
Cotton shirt, 10% WOF
Cotton broadcloth, 10% WOF
Fill your dye pot with enough warm water for your fibers to move around freely.
Weigh out the appropriate weight-of-fabric (WOF) of Oak Gall Extract. Use 5% for a medium beige or 10% for a dark beige.
Blend the Oak Gall Extract with a little water to make paste. Be sure to break up any clumps of powder — otherwise they might cause dark spots on your fiber. Add the paste to the dye bath and mix well until dissolved.
Gently add your scoured cotton or linen fibers.
Gradually heat the dye bath to a boil, stirring regularly so that the cotton dyes evenly. When it just reaches a boil, lower the heat to about 200F (a gentle simmer) and maintain for 30 minutes. Stir regularly to make sure the fibers dye evenly.
After 30 minutes, remove the dye pot from the heat. Cover and allow to cool down to room temperature. The plant fibers will absorb a significant amount of tannins during this cooling-off period. Uncover the pot and stir occasionally to make sure the fibers dye evenly. If the dye bath cools down very quickly, steep for at least 3 hours.
[Optional] The darkest results will be obtained by letting the fibers steep in the dye bath overnight. However, the trade-off is that the results may be uneven, especially if any bubbles get trapped under the fiber or if some of the fiber is not submerged completely. If you plan to let the fibers steep overnight, make sure they are all evenly submerged and no bubbles are trapped beneath them before going to bed.
When finished steeping, remove the cotton. If you plan to stop here (and not continue on to mordanting), rinse the fibers well in warm water with 1 tsp of pH-neutral detergent per pound of cotton (we use Synthrapol). Follow the manufacturer’s directions for best results. Rinse again in a few changes of warm water until all soap suds are rinsed out and the water runs clear. CAUTION: Oak Gall Extract may bleed if not thoroughly rinsed out after dyeing. Hang up to dry out of direct sunlight.
[Optional] If you plan to continue on to mordanting the fibers with iron or alum, do not rinse them. Much of the tannin that is soaked into the fibers is not yet permanently fixed and it will wash out if rinsed, resulting in more pale colors at the end of the dyeing process. Instead, remove the fibers from the dye bath and gently squeeze out excess liquid while wearing rubber gloves. Proceed directly to mordanting them with iron (see Section 5: Greige).
5. Greige on Cotton/Linen
When plant fibers like cotton and linen are dyed with a tannin-rich compound like Oak Gall Extract, they can be mordanted much more easily. Since Oak Gall Extract already gives fibers a brownish shade (in contrast to clear tannins like Sumac Extract or Oak Gall Extract Light) it makes sense to use it as a base for dying darker shades, especially the moody hues produced with iron. The first step is to “sadden” the fibers with iron, which will shift the brown hue toward a warm gray or greige. Iron is also very easy to apply to tanned cotton and linen, because it does not require heat. You can either stop here and enjoy the subtle shades of greige, or continue afterwards to dyeing with a dye like Royal Logwood Extract (see Section 6).
Cotton Shirt, 4% WOF
Cotton Broadcloth, 4% WOF
Cotton Shirt, 8% WOF
Cotton Broadcloth, 8% WOF
Follow the directions for Beige in Section 4. After dyeing, gently wring the cotton out, but do not rinse it.
Fill a dye pot or plastic bucket with enough room temperature water for your fibers to move around freely.
Weigh out the appropriate weight-of-fabric of iron mordant (ferrous sufate). The correct amount will depend on how much Oak Gall Extract was used to dye the fibers. If 5% Oak Gall Extract was used, weigh out 4% ferrous sulfate. If 10% Oak Gall Extract was used, weigh out 8% ferrous sulfate.
Add the iron mordant to the dye pot or plastic bucket and mix well until dissolved* [see Note 1].
Gently add your wetted, dyed cotton fibers.
Wearing rubber gloves, work the cotton in the iron bath for a minute or two to make sure the iron solution penetrates the cotton completely. It should quickly turn gray.
Let the cotton steep in the iron bath for 1 hour (for thin cotton, such as a t-shirt) or up to 2 hours (for very thick or densely woven fabrics). Wearing rubber gloves, move it around occasionally to make sure it mordants evenly. Be careful not to let bubbles get trapped under the fiber, and try to keep all the cotton submerged.
After 1 to 2 hours, the cotton will have permanently saddened to a gray shade. Wearing rubbers gloves, remove and rinse well in warm water with 1 tsp of pH-neutral detergent per pound of cotton (we use Synthrapol). Follow the manufacturer’s directions for best results. Rinse again in a few changes of warm water until all soap suds are rinsed out and the water runs clear [see Note 2].
Hang up to dry out of direct sunlight.
NOTE 1: Most of the steps of dyeing with a tannin like Oak Gall Extract could be called “water agnostic,” that is, they should work regardless of if your water is hard or soft or acidic or alkaline. However, the iron mordant bath in this step needs to be made with soft water. If ferrous sulfate powder is mixed into hard water, it will turn brown and cloudy because the iron will precipitate with the calcium in the hard water, rendering the iron much less effective as a mordant. If your mordant bath remains relatively translucent, with a yellowish or greenish cast, it will work fine; but if it looks like it is full of rust particles, the water is too hard and a different water source will need to be used. If necessary, the cheap bottled drinking water from your local big box store should work perfectly well.
NOTE 2: The saddened cotton or linen should be thoroughly rinsed at this point, regardless of if you plan to stop here or proceed to dyeing it. We did not rinse the fibers after the initial dyeing/tanning step because we did not want to rinse out unbound tannins. At this stage however, any unbound mordant should be rinsed out thoroughly, as it will only cause trouble later on, potentially wasting dye in the dye bath or causing the color to crock.
6. Copperas Black
After completing the previous recipe, the cotton fibers are not only dyed gray, they are also mordanted with iron, which means they can be dyed with other natural dyes which need a mordant to function properly. Any appropriate mordant dye could be used, but the most common in this instance would be logwood. Mordanting cotton with tannin and iron was traditionally the first step for dyeing a copperas black (logwood black). The following recipe uses Royal Logwood Extract to dye a typical copperas black, although an equivalent quantity of Logwood Shavings or Campeche Blue could be used for the same purpose.
Cotton Shirt, 1% WOF
Cotton shirt, 2% WOF
Follow the directions for Greige in Section 5. After saddening the cotton with iron, rinse well with warm water and soap as described, but do not let the fibers dry. After they are rinsed, proceed directly to dyeing.
Fill a dye pot with enough room temperature water for your fibers to move around freely.
Weigh out the appropriate weight-of-fabric of Royal Logwood Extract. The correct amount will depend on how much Oak Gall Extract was used to dye the fibers. If 5% Oak Gall Extract was used, weigh out 1% Royal Logwood Extract. If 10% Oak Gall Extract was used, weigh out 2% Royal Logwood Extract.
Add the Royal Logwood Extract to the dye pot and mix well until dissolved.
[Optional] If you have very soft water, add 1 gram of chalk (calcium carbonate) to the dye bath and mix well until dissolved. Logwood gives the best results in a calcium-rich dye bath.
Gently add your wetted, iron-mordanted cotton fibers to the dye bath
Gradually heat the dye bath to 180F, stirring regularly so that the cotton dyes evenly. Maintain this temperature for one hour.
After one hour, turn off the heat and let cool until the cotton can safely be handled. Remove and rinse well in hot water with 1 tsp of pH-neutral detergent per pound of cotton (we use Synthrapol). Follow the manufacturer’s directions for best results. Rinse again in a few changes of warm water until all soap suds are rinsed out and the water runs clear. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed out after dyeing.
Hang up to dry out of direct sunlight.
7. Rustic Red
Oak Gall Extract can also be used as a base for mordanting cotton or linen with aluminum. However, since it imparts a brown shade to the fibers, it will work best with dyes that combine well with a brown undertone. Once the fibers are mordanted with aluminum any natural dye could be applied, but we have combined it here with a little madder root to produce an earthy red tone reminiscent of the rustic textiles found in Indian villages. Note that the main difference between mordanting with aluminum lactate and mordanting with iron is that we will need to apply heat to fix the aluminum lactate to the fiber.
Cotton Shirt, 30% WOF
Cotton broadcloth, 30% WOF
Follow the directions for Beige in Section 4. After dyeing, gently wring the cotton out, but do not rinse it. Proceed directly to mordanting. For best results, do not allow the cotton to dry out first.
Fill a dye pot with enough warm water for your fibers to move around freely.
Weigh out 10% weight-of-fabric (WOF) of aluminum lactate. Add to the dye pot and mix well until dissolved.
Heat the aluminum lactate mordant bath to 150°F or 160°F — hot, but not boiling. Adding the plant fibers to an already hot mordant bath will make sure that the reaction happens quickly, so there is little time for unfixed tannins to wash out of the plant fibers before they have had a chance to bond to the aluminum mordant.
Gently add your wetted, oak gall-treated plant fibers.
Raise the heat to 200°F (a gentle simmer) and maintain for 30 minutes, stirring occasionally to make sure that the fibers mordant evenly.
After 30 minutes, remove from heat and allow to cool
When cool enough to handle safely, remove the plant fibers and rinse well in several changes of hot water. You may wish to rinse with soap at this stage. For example, use 1 tsp of pH-neutral detergent per pound of cotton (we use Synthrapol). Follow the manufacturer’s directions for best results. Rinse until all soap suds are rinsed out and the water runs clear [see Note].
Proceed directly to dyeing. Build a dye bath using the natural dye of your choice; see individual guides for recommendations on how much of each dye to use and what temperature to use. As an example, for Rustic Red we have used 30% Madder Root. When the dye bath is ready, gently place the mordanted plant fibers into the dye bath and heat as required. After dyeing, rinse well with 1 tsp of pH-neutral detergent per pound of cotton or linen. Follow the manufacturer’s directions for best results.
Hang up to dry out of direct sunlight.
NOTE: The cotton or linen should be thoroughly rinsed after mordantingt. We did not rinse the fibers after the initial dyeing/tanning step because we did not want to rinse out unbound tannins. At this stage however, any unbound mordant should be rinsed out as well as possible, as it will only cause trouble later on, potentially wasting dye in the dye bath or causing the color to crock. Using soap or detergent is optional, but it can help remove excess mordant more quickly.
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