What is natural dye?

Natural dyes are colors that are extracted from plants (and insects). They are fixed through the use of mordants. Mordants are metal salts and tannins. Some metal salts are; alum (aluminum sulfate), iron (iron sulfate). Tannic acid and myrobalan are tannins that are used to fix dyes to cellulose (plant) fibers. Natural dyes have been used for thousands of years to produce color, and it is only in the past 100 years that synthetic dyes were invented. Natural dyes are a safer and less costly alternative, and once the fiber is prepared to accept the dye, there are many colors that can be achieved.



How is the dye made?

Common vegetables, plants, barks, berries, insects, and lichens can be used as natural dye sources. The main source for our dyestuff is the GrowNYC greenmarket where we find plants and vegetables that are in season and are of local origin. The dyestuffs or plant matter is boiled in water to extract the dye. The material to be dyed is first “mordanted” with the chosen metal salt or tannin by heating it in water with the mordant.




Observe safety when dealing with plants because some can cause allergic reactions. WEAR RUBBER GLOVES throughout all stages of the natural dye process. In the dye process, mordant salts are usually the most toxic problem. Do not use the same pots and utensils that are used for cooking.




Proper cleaning is essential for the dye and mordants to absorb into the fiber. Synthrapol or Woolite can be used at a ratio of 1 tsp per pound of fiber.


Use a large vessel so the fiber can move around freely.


Add water an 1 tsp of Synthrapol


Slowly heat up and simmer fiber for 1 hr. IMPORTANT: when scouring wool bring the temperature up slowly and allow the fiber to cool completely before rinsing. DO NOT AGITATE. DO NOT BOIL.




There are two kinds of natural dyes. SUBSTANTIVE dyes do not need mordants to fix to the fiber. Some substantive dyes are black walnuts, fustic, myrobalan and indigo. Most plant dyes are ADJECTIVE dyes, and they require a mordant. The mordant joins the fiber to the dye to permanently fix it. There are different mordants and each will draw out a different shade of color. There are some metal mordants that are toxic such as copper, tin and chrome. Since these mordants are bad for our bodies and the environment, we only use alum, iron, and tannin. Typically, Alum (aluminum sulfate) and Iron (ferrous sulfate) are used for wool, while tannin, myrobalan, alum and iron can be used for cotton.


ALUM – Potassium aluminum sulfate is the mordant most frequently used for protein fibers. It can also be used with cottons in combination with a tannin mordant DONE IN SEPARATE BATHS. Alum keeps colors clear (does not tint).


TANNIN – tannic acid is a mordant used with cellulose fibers before alum. Alum does not bond as easily to cellulose fibers as it does with protein fibers. Many dyes contain tannin content and they do not need additional tannin mordant.


MYROBALAN – this dye is from the nuts of the Terminalia chebula tree, which grows in Asia. It may be used as both a mordant and a dye,, giving a buttery yellow color to the fiber. The color works well for over dyeing and imparts a warm yellow color on the fiber. When used as a tannin mordant use at 15% WOF (weight of fiber). As a dye use at 20% WOF.


IRON – Ferrous sulfate is a mordant that helps with color and light fastness, and is used as a color changer. It works very well on cellulose fibers and should be used with care on protein fibers, because it can make them brittle. Iron shifts the color to a deeper, darker shade, often called “Saddening” the color.



Mordanting Wool, Silk, and other Protein Fibers

1.Weigh out the fiber. This is the WOF “weight of fiber”.
2. Measure alum at 15% WOF, or iron at 2%.
3. Dissolve mordant in a non-reactive container.
4. Add the dissolved chemical to a dye pot with enough water to cover the fiber.
5. SLOWLY bring the temperature up to a low simmer (45 min).
6. Allow to cool (20 min).
7. Rinse fiber before submerging into dye solution.



Mordanting Cotton & Other Cellulose Fibers

Tannin (tannic acid) is one of the few mordants readily absorbed by cellulose fibers. Once mordanted with tannin, other mordants combine well with the fiber.
1. Weigh out the fiber (WOF)
2. Measure tannin at 10% WOF. (Myrobalan at 15% WOF)
3. Dissolve mordant in a non-reactive container (stainless steel, plastic, glass or enamel).
4. Add the dissolved chemical to a dye pot with enough water to cover the fiber.
5. SLOWLY bring the temperature up to a low simmer (45 min).
6. Allow to cool (20 min).
7. Rinse fiber before submerging into dye solution.


The method outlined above is called pre mordanting (mordanting prior to dyeing). This is the method most frequently used. Occasionally the mordant is added directly to the dye bath, this is called meta mordanting. Mordants can also be added to the fiber after dyeing (post mordanting).


Use the ratios
Alum at 15% WOF
Iron at 2% WOF
Tannin at 10% WOF
Myrobalan at 15% WOF
(Weight of Fiber x %= weight of mordant or dyestuff)



Other Additives

Cream of Tartar or Tartaric Acid – This helps soften the fiber when harsh mordants are used (iron). Cream of Tartar also helps brighten reds and yellows (it will turn the color of cochineal to a true red). Use in the ratio of 6% WOF.


Vinegar (acetic acid) – This is used in small quantities to help wool and silk absorb the dye. It can also be used as an after bath to alter the dye coior.


Lemon Juice (Citric Acid) – This is used to alter the color of some dyes. It can be used as an after bath, or added to the dye pot.


Soda Ash – This is used to alter the color of some dyes. Add to the dye bath to create a more alkaline dye liquor.




All dyeing should be done in a non-reactive dyepot of stainless steel. If you use iron, aluminum, or copper pots they will alter the color of the dye.