Royal Logwood Extract
Royal Logwood Extract
INTENSE PURPLES, BLUES, AND BLACKS
Shepherd Textiles Royal Logwood Extract is made from the wood of haemotoxylin campechianum, the Campeche logwood tree. Logwood contains a potent natural pigment called hematine that can develop into intense shades of purple, blue, and black. The color is determined by the mordant—alum gives royal purples and navy blues, while iron yields grays and blacks. Royal Logwood Extract is made in the USA from imported logwood and is very concentrated. Use it at just 1% weight-of-fabric (WOF) for deep colors. An excellent choice for all natural fibers including wool, cotton, and silk. Note that logwood requires a mordant to function as a dye.
1. Background on Logwood
The logwood tree, haemotoxylin campechianum, is native to southern Mexico and the Yucatan peninsula. Its use as a dye was well-known to the prehispanic Maya, and Spanish explorers began trading for it as early as 1502. Logwood quickly became one of the major exports of New Spain, along with silver and cochineal, because for several centuries it was the only reasonable source of purple and black dye. Contemporary sources describe Spanish galleons crossing the Atlantic with the decks piled high with logwood timber, and logwood ships were one of the major targets of English pirates along the Spanish Main (Ortiz-Hidalgo and Pina-Oviedo 2019:4). The port of Campeche on Mexico’s Gulf Coast controlled most of the logwood trade in the 17th and 18th centuries, hence why logwood is sometimes referred to as Campeachy Wood. The botanical name, haemotoxylin, is Greek for blood-tree, referring to the dark color of the heartwood after it oxidizes.
The heartwood of the logwood tree contains a potent compound called haemotoxylin. After it is extracted by boiling (or, today, by steam extraction) it is exposed to air and oxidizes into the pure dyestuff called hematine. Hematine is a powerful dye on all natural fibers, even cellulose fibers like cotton that are often resistant to natural dyes. However, it requires a mordant to bond effectively to fiber. Alum gives rich purples, although they have a reputation for fading in sunlight. Copper yields blues that Victorian dyeing houses celebrated for their strength and lightfastness. Iron gives grays and true black. Logwood was mostly abandoned after aniline black dye was invented in 1865, but it is still used today to safely dye medical sutures black so they can be seen more easily.
2. Safety Precautions
This product is intended for textile projects only.
Do not ingest.
Avoid eye contact. If eye contact occurs, rinse well with cool water.
Avoid direct skin contact. If skin contact occurs, rinse well with cool water.
Wear gloves, a mask, and eye protection while handling the dry pigment. Work in a well-ventilated space, and wash hands after use.
Not for use in food, cosmetics, soap, or hair care products.
Open carefully to avoid spilling or creating dust. If a spill occurs, quickly wipe up with a paper towel or disposable rag.
Royal Logwood Extract can permanently dye clothing, countertops, rugs, utensils, or other property. Avoid contact with anything 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.
Metal mordants like ferrous sulfate are irritants and may be harmful if swallowed. Read your manufacturer’s safety data sheet (SDS) before use.
Royal Logwood Extract, 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.
4. Recommended Supplies
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. Logwood extract may leave faint stains on metal dye pots. If so, the stain can usually be scrubbed out with a scouring pad.
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 extract powder and while handling mordanted/dyed fiber before it is rinsed.
Candy thermometer. Royal Logwood will lose some of its clarity if the dye bath gets hotter than 175F. The best way to keep track of temperature is to use a cheap candy thermometer that clips to the side of the dye pot.
Scale. Use a scale to weigh out fiber, mordant, and extract powder.
Alum, copper, or iron mordant. The color produced by logwood is determined by the mordant used. For purples, use aluminum potassium sulfate, also known as potash alum. It is the same alum that you can find in a jar in the spice section at the grocery store.
PH strips. For adjusting the dye bath PH.
Disposable cup. For mixing the extract powder to a paste.
4. Preparation: Mordanting
Logwood only bonds effectively to fibers that have been mordanted; otherwise it just produces a faint brown. Alum, copper, and iron mordants will all yield different shades. For best results, soak your fibers in water for a few hours before mordanting, so that the mordant will penetrate deeply and evenly. Make sure to weigh the fibers first, while they are still dry.
Mordant powders will dissolve quickly into hot tap water.
Heat fibers to 180F.
For protein fibers (wool, silk, alpaca): Mordant at 12% WOF with alum or 2% WOF with copper or iron.
Weigh out the fibers you plan to dye (while they are dry). Multiply that weight by 0.12 to get the amount of alum you will need, or by 0.02 to get the correct amount of copper or iron*. Wear gloves, eye protection, and a mask while handling metal powders.
Fill your dye pot with hot tap water, leaving enough room for the fiber.
Weigh out the correct amount of mordant powder and pour it into the dye pot. Mix with a spoon or metal tongs until it has dissolved.
Gently place your wetted fibers into the mordanting solution.
Heat mordant bath to 180F. If you don’t have a candy thermometer, you will have to estimate the temperature. At 180F, steam vapor will be rising off the water but it will not be bubbling. If your mordant bath starts to bubble, turn down the heat.
Maintain heat for 1 hour (alum and copper) or 30 minutes (iron). Stir occasionally to make sure the fibers mordant evenly. If they do not, the dye will take better in some places than others.
After 1 hour (alum and copper) or 30 minutes (iron), remove from heat and allow to cool. Fibers can be left to steep in an alum or copper bath overnight to improve mordant penetration. This can be useful when dyeing thick or tightly woven fabrics. However, fibers should be removed from an iron bath as quickly as possible to prevent corrosion or damage.
Remove cooled fibers. Wearing rubber gloves, gently squeeze excess mordant solution back into the pot. Rinse well in lukewarm water. The fiber does not need to be washed with detergent, but any excess mordant should be rinsed out. This is especially important for iron, because unbonded particles can damage the fiber if they are not washed off.
Set rinsed mordanted fibers aside until ready to dye. Keep out of reach of children and pets.
Dispose of mordant solution according to local guidelines.
For cellulose fibers (cotton, linen, etc.): Pre-treat with a tannin before mordanting with alum, copper, or iron.
Cellulose fibers are more resistant to mordants than protein fibers, and may require pre-treatment with a tannin to absorb mordants effectively. In our experience, success dyeing cellulose fibers depends very much on the quality of fiber used. Handspun, handloom, and organic cotton and linen tend to take natural dyes well, and you can skip the optional tannin step and still get good results. However, commercial cotton tends to be more resistant to natural dyes, possibly because of industrial finishing. It will often need to undergo a two-step mordanting process.
Scour cellulose fibers well. Traditionally this is done in a highly alkaline soda ash solution, but standard household detergents like Tide© are equally alkaline (PH 11), so we prefer to just toss the fiber in the washing machine on an high-temperature cycle with plenty of detergent.
[OPTIONAL] Apply a clear or light-colored tannin to the scoured fabric. Some good choices are Gallnut Extract, Tara, Sumac, or Myrobalan. To use, fill your dye pot with hot water, dissolve 2-5% WOF of your chosen tannin in the dye bath (check vendor’s instructions—each will need a slightly different WOF) and simmer for an hour. Be very careful to keep the fiber moving around: some tannins have insoluble particles that love to get stuck in fabric, and they can cause splotches later on in the dyeing process. After an hour, let cool, remove fibers and rinse well.
Mordant as described above for protein fibers. Use the same percentages of each mordant: 12% alum, 2% copper, or 2% iron.
*CAUTION: Copper powder (copper sulfate pentahydrate) and iron powder (ferrous sulfate) are both irritants, and may be harmful if ingested. Please read your manufacturer’s safety data sheet (MSDS) before using. Wear gloves, a mask, and eye protection whenever handling metal powders, and do not handle the mordanted fibers with bare hands until they have been rinsed. Keep mordant powders, mordant baths, and unrinsed mordanted fibers away from children and pets.
Recipes
5. Purple on Woolens
Logwood is probably best known for the purple colors that develop when it is paired with an aluminum mordant. This is a simple recipe but by varying the amount of dye used, many different shades of purple and lavender can be produced. Logwood is very sensitive to pH — acids will shift the color toward a reddish shade of purple, and alkalis will shift it nearly to blue, so the exact shade you get may depend on your water chemistry. Note that logwood purple has modest fastness to light: if left in the sun the color will lose its intensity and fade to a purple-brown shade.
Wool yarn, 0.5% WOF
Wool yarn, 1% WOF
Fill your dye pot with enough warm water for your fibers to move around freely.
[Optional] Add 1 gram of calcium acetate per gallon of water in the dye pot. Logwood requires calcium in the bath to develop an intense color. The trace amount of calcium in most tap water is sufficient, but it you have very soft water, or you are working with distilled or reverse osmosis filtered water, you will need to add extra calcium. For dyeing purples, calcium acetate is the best form of calcium to use because it will not raise the pH of the dye bath.
Weigh out the appropriate weight-of-fabric (WOF) of Royal Logwood Extract powder. Use 0.5% for a lighter purple shade or 1% for dark purple. Add the powder to the dye bath and mix well until any clumps are dissolved.
Add your wetted, alum-mordanted wool to the dye bath.
Heat the dyebath to 170°F very gradually, over the course of about 30 minutes, stirring regularly so that the wool dyes evenly. Maintain this heat for 1 hour and continue to stir occasionally. After 1 hour, turn off the heat and allow to cool to room temperature.
When the wool is cool enough to handle safely, remove with tongs and rinse well in warm water until the water runs clear. Soap or detergent should not be necessary, because the color in the dye bath should have mostly exhausted onto the wool. However, if necessary, wash with a pH-neutral detergent like Synthrapol. Follow the manufacturer’s directions for best results. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed.
Hang up to dry out of direct sunlight.
6. Blue(ish) on Woolens
Logwood can also be used to dye a beautiful blue shade on woolen fibers — but only on woolen fibers (cotton, linen, and silk dyed the same way will come out purple). Chalk is used to raise the dye bath to a very slightly alkaline pH, which causes the normal purple hue to shift toward blue. Note that this blue is right on the edge of the purple spectrum: in sunlight you may look at it and say, “That’s definitely blue!” but in artificial light you might look at the same wool and think, “that’s a very blueish shade of purple.” If you need a blue without the purple undertone, use Campeche Blue Extract instead. This is an extremely beautiful color, especially when freshly dyed, but it has modest lightfastness and will fade if left in the sun.
Wool yarn, 0.5% WOF
Wool yarn, 1% WOF
Fill your dye pot with enough warm water for your fibers to move around freely.
[Optional] Add 1 or 2 grams of calcium carbonate (chalk) per gallon of water in the dye pot. The exact amount required will depend on your water source; most tap water already has some calcium in it, so adding 1 gram of chalk per gallon should be enough. If you are using distilled or reverse osmosis filtered water, or your water is very soft, use 2 grams per gallon. The chalk not only adds the necessary calcium, it is also a mild alkali that buffers the pH at the right level to shift logwood from purple to blue. This step is optional if you already have extremely hard, alkaline water (such as we have in north central Washington) in which case you may not need to add the chalk.
Weigh out the appropriate weight-of-fabric (WOF) of Royal Logwood Extract powder. Use 0.5% for a periwinkle shade or 1% for a navy blue. Add the powder to the dye bath and mix well until any clumps are dissolved.
Add your wetted, alum-mordanted wool to the dye bath.
Heat the dyebath to 170°F very gradually, over the course of about 30 minutes, stirring regularly so that the wool dyes evenly. Maintain this heat for 1 hour and continue to stir occasionally. After 1 hour, turn off the heat and allow to cool to room temperature.
When the wool is cool enough to handle safely, remove with tongs and rinse well in warm water until the water runs clear. Soap or detergent should not be necessary, because the color in the dye bath should have mostly exhausted onto the wool. However, if necessary, wash with a pH-neutral detergent like Synthrapol. Follow the manufacturer’s directions for best results. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed.
Hang up to dry out of direct sunlight.
7. Black on Woolens
When logwood is combined with an iron mordant it produces fine, lightfast shades of gray and black. In fact this was the most important use of logwood historically, before it was displaced by synthetic dyes at the end of the 19th century. This color was known to dyers as “copperas black,” although in fact it is really a very dark blue-black shade. The blue undertone was generally considered to make it more beautiful than a flat, matte black, and this color was always in high demand. It is simple to dye, the only difference with the previous recipes being that the wool is premordanted with iron rather than aluminum. The recipe can be varied endlessly to adjust the hue of the black color — see the note at the end of the recipe for details.
Wool yarn, 0.5% WOF
Wool yarn, 1% WOF
Fill your dye pot with enough warm water for your fibers to move around freely.
[Optional] Add 1 gram of calcium acetate or calcium carbonate per gallon of water in the dye pot. Logwood requires calcium in the bath to develop an intense color, including an intense black. The trace amount of calcium in most tap water is usually sufficient, but it you have soft water, or you are working with distilled or reverse osmosis filtered water, you will need to add extra calcium. For dyeing black, either calcium acetate or calcium carbonate can be used, although calcium carbonate will tend to deepen the blue undertone. Note that adding calcium may be optional if you already have extremely hard water.
Weigh out the appropriate weight-of-fabric (WOF) of Royal Logwood Extract powder. Use 0.5% for a blue-gray shade or 1% for black [see Note 1]. Add the powder to the dye bath and mix well until any clumps are dissolved.
Add your wetted, iron-mordanted wool to the dye bath.
Heat the dyebath to 170°F very gradually, over the course of about 30 minutes, stirring regularly so that the wool dyes evenly. Maintain this heat for 1 hour and continue to stir occasionally. After 1 hour, turn off the heat and allow to cool to room temperature.
When the wool is cool enough to handle safely, remove with tongs and rinse well in warm water until the water runs clear. Soap or detergent should not be necessary, because the color in the dye bath should have mostly exhausted onto the wool. However, if necessary, wash with a pH-neutral detergent like Synthrapol. Follow the manufacturer’s directions for best results. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed.
Hang up to dry out of direct sunlight.
NOTE 1: This recipe (logwood on an iron mordant) is the basic foundation for dyeing black on wool. However, it produces a black with a blueish undertone, which is beautiful but may not be what you are aiming for. Historically there were countless variations on this recipe to get different shades of black. Some dyers added a little of a yellow dye to the dye bath to make the black appear more neutral (French Weld Extract would be a good choice). Other dyers would add a little madder, or a little copper at the end of dyeing, or dye the wool first with indigo, or simply use more logwood (in which case the amount of mordant should be increased as well). This recipe is a good base that can be modified in endless ways to get a black suitable for a particular project.
8. Purple on Cotton/Linen
When combined with an aluminum mordant, logwood produces various shades of purple on plant fibers like cotton and linen. The color is still pH-sensitive, but not nearly as much as when it is dyed on wool (on cotton the color cannot be pushed all the way to blue — it will always be a warmer or cooler shade of purple). The color can also be slightly modified depending on how the cotton is mordanted, and whether it is treated with a tannin before mordanting. Logwood is probably one of the easier natural dyes to use on plant fibers because it is fairly forgiving of imperfect mordanting. This is a beautiful, strong color, but it has modest fastness to light and the color will fade to a purplish brown if it is left in the sun.
Oak Gall Light + Aluminum Formate Pro + 2% WOF
Oak Gall Light + Aluminum Acetate + 3% WOF
Prepare the cotton or linen fibers first by mordanting them with an aluminum mordant for plant fibers such as Aluminum Acetate or Aluminum Formate Pro. See the guides for those mordants for complete details. For the darkest purples, treat the fibers with a tannin like Oak Gall Light or Sumac Extract before mordanting.
Fill your dye pot with enough warm water for your fibers to move around freely.
[Optional] Add 1 gram of calcium acetate or calcium carbonate per gallon of water in the dye pot. Logwood requires calcium in the bath to develop an intense color. The trace amount of calcium in most tap water is usually sufficient, but it you have soft water, or you are working with distilled or reverse osmosis filtered water, you will need to add extra calcium. For dyeing cotton, either calcium acetate or calcium carbonate can be used. Note that adding calcium may be optional if you already have extremely hard water.
Weigh out the appropriate weight-of-fabric (WOF) of Royal Logwood Extract powder. Use 0.5% to 1% for a lavender or medium purple shade, or 2-3% for a dark purple. The ideal amount will vary depending on the thickness of the fiber and how it was mordanted. Add the powder to the dye bath and mix well until any clumps are dissolved.
Add your wetted, alum-mordanted cotton or linen to the dye bath.
Heat the dyebath to 180°F very gradually, over the course of about 30 minutes, stirring regularly so that the cotton or linen dyes evenly. Maintain this heat for 1 hour and continue to stir occasionally. After 1 hour, turn off the heat and allow to cool to room temperature.
When the fibers are cool enough to handle safely, remove with tongs and rinse well in warm water until the water runs clear. Soap or detergent may not be necessary if the color in the dye bath has mostly exhausted onto the fibers. However, if dyeing darker shades, you may need to wash the fibers with a pH-neutral detergent like Synthrapol. Follow the manufacturer’s directions for best results. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed.
Hang up to dry out of direct sunlight.
9. Black on Cotton/Linen
Logwood produces good gray and black shades on cotton or linen that are mordanted with iron. The fibers will need to be treated with a tannin before they are mordanted, and different tannins will result in slightly different hues of black on the finished piece. Brownish tannins like Oak Gall Extract and Myrobalan produce a more neutral black, whereas clear tannins like Oak Gall Light and Sumac Extract will let the blue undertone show through a bit more. Any tannin is suitable, except for tara tannins which behave unpredictably with iron. The black that is dyed with iron is much more lightfast than the purple that is dyed with aluminum, although the black will still tend to lose some of its intensity if left in the sun.
Oak Gall Extract + Iron + 1% WOF
Oak Gall Extract + Iron + 2% WOF
Prepare the cotton or linen fibers first by mordanting them with iron (ferrous sulfate). See the guide for Ferrous Sulfate for complete details. Scour the fibers, then treat them with a tannin like Oak Gall Extract or Sumac Extract overnight. The next day, make a bath containing 5% weigh-of-fabric (WOF) of ferrous sulfate powder. Gently squeeze the tanned fibers, then place them in the ferrous sulfate bath at room temperature for two hours, stirring occasionally so that they mordant evenly. After two hours, remove the fibers and rinse well before proceeding.
Fill your dye pot with enough warm water for your fibers to move around freely.
[Optional] Add 1 gram of calcium acetate or calcium carbonate per gallon of water in the dye pot. Logwood requires calcium in the bath to develop an intense color. The trace amount of calcium in most tap water is usually sufficient, but it you have soft water, or you are working with distilled or reverse osmosis filtered water, you will need to add extra calcium. For dyeing cotton, either calcium acetate or calcium carbonate can be used. Note that adding calcium may be optional if you already have extremely hard water.
Weigh out the appropriate weight-of-fabric (WOF) of Royal Logwood Extract powder. Use 1% for a gray shade, or 2-3% for black. Add the powder to the dye bath and mix well until any clumps are dissolved.
Add your wetted, iron-mordanted cotton or linen to the dye bath.
Heat the dyebath to 180°F very gradually, over the course of about 30 minutes, stirring regularly so that the cotton or linen dyes evenly. Maintain this heat for 1 hour and continue to stir occasionally. After 1 hour, turn off the heat and allow to cool to room temperature.
When the fibers are cool enough to handle safely, remove with tongs and rinse well in warm water until the water runs clear. Soap or detergent may not be necessary if the color in the dye bath has mostly exhausted onto the fibers. However, you may need to wash the fibers with a pH-neutral detergent like Synthrapol. Follow the manufacturer’s directions for best results. CAUTION: Royal Logwood Extract may bleed if not thoroughly rinsed.
Hang up to dry out of direct sunlight.
*All text and images are copyright of Shepherd Textiles, LLC. Do not reproduce without permission and attribution.