Natural Dye Mordant and Wash Instructions
Preparing Yarn and Fiber for Dyeing
These natural dye mordant and wash instructions are focused on wools and silk since they dye the best with natural dyes. If dyeing cellulose fibers, please pay close attention to additional notes. For more information on natural dye mordants please see this
Important note: Weigh the amount of yarn or fiber you plan to dye before making it wet. Amount of mordant and dyestuff to use is based on a percentage of the dry weight of your material.Washing
Wash your fibers/yarns even if they look really clean. A little oil is used when fibers are carded and spun and this could interfere with dye take up. Mild soaps are best – if you don't have one specifically for washing fibers, a little dish soap will do. Protein fibers, especially wool, are weaker when wet so avoid too much agitation in water and don't wring out. Also avoid extreme temperature changes which result in shrinking and felting. Superwash wools are chemically treated and tolerate more handling.
If washing raw fiber, especially a greasy wool, you will likely need a stronger scouring agent to clean and hotter water than described below.
Silk also does not shrink and can tolerate hotter water but do not boil. Over 80C will cause it to lose some of it's sheen.
Cellulose fibers should also be well washed. Cotton has natural waxes that need to be removed. Because these fibers tolerate so much more handling and don't shrink, they can be boiled for about an hour with mild soap and a little washing soda.
carries Synthrapol, a well-known soap for fibers. They have also recently developed their own brand similar to Synthrapol but less expensive and more environmentally friendly.
Directions: For wool, fill a tub with warm water and a small amount of soap. Gently submerge the yarn and let it soak for at least 20 minutes. Remove yarn and refill with clean water. Gently swish the yarn in rinse water as often as necessary until soap has been removed. If not mordanting and dyeing right away, hang yarn or lay out fiber to dry. To speed this up, you can gently place it in your washing machine and run it through the spin cycle only. Material does need to be pre-wetted for mordanting and dyeing. Presoak for at least 30 minutes.
Superwash wools, silk and cellulose fibers can tolerate hot water for cleaning. Cotton close to it's raw state should be boiled for about an hour with washing soda and soap to remove any natural waxes.
Mordanting helps the dye bind to the fiber. It is as important as the dye process itself. Different mordants allow different colour ranges for each dyestuff. There are mainly two categories of natural dye mordant, plant and mineral. Some of the mineral mordants are considered toxic and their use is limited or avoided. Historically cultures have used a variety of mordants including blood, urine and manure. The amount of mordant used is a percentage of the weight of fiber. For example, based on 4% weight of wool, use 4 gms of Herbal Mordant per 100 gm of wool (or about 1/2 oz per pound of wool). Or for Alum, based on 10% weight of wool, use 10 gms alum per 100 gms of wool (or 1½ oz alum per pound of wool).
Directions for Herbal Mordant: Measure out 4% of herbal mordant per weight of dyeing material and mix with enough hot water to make a thin paste. Begin heating large pot of water (enough water to allow material to move freely) and add a small amount of vinegar or acetic acid to make the water pH 4.* When water reaches about 60C, add the mordant paste and stir well. Then add the pre-wetted fiber or yarn. Bring to a simmer, about 80C (180F) and simmer for 30 minutes, moving the fiber around regularly. Remove from heat and allow to cool back down to 60C. Remove material and allow to cool to room temperature. Wash with water and the material is ready for dyeing.
*Note that cellulose fibers like cotton dye best in alkaline water - about pH8 - so do not add vinegar. Instead add washing soda (soda ash, sodium carbonate). It is very useful to have a pH meter.
Directions for Tannic Acid: Measure out 10% tannic acid per weight of dyeing material and mix with small amount of hot water to dissolve. Add to pot of water and mix well. Add pre-wetted material and slowly heat to simmer, about 80C (180F). Simmer about 30 minutes, stirring material regularly. Allow to cool then remove material and rinse well. Tannic acid is most commonly used for the cellulose fibers, ie. cotton, linen, hemp. Some washing soda added to the water will help alkalinize to about pH8 if dyeing cellulose.
Directions for Alum mordant: Alum is usually used along with cream of tartar as an 'assistant'.* Use from 10-25% alum per weight of dyeing material (but not more than that as mineral mordants can damage the fiber). Add about ¼ that amount of cream of tartar. Dissolve together in a little hot water, then add to cool water pot and mix. Add the pre-wetted material and slowly raise the temperature to a simmer, about 80C (180F). Simmer for 30-45 minutes, moving the fiber around regularly. Allow to cool, then remove the fiber and rinse it well – fiber is ready for dyeing.
*Do not use cream of tartar for cellulose fibers, like cotton as it helps to acidify the water. Cellulose fibers require an alkaline bath, so instead washing soda can be added to reach pH8.
Alum mordanting can also be done in cool water for longer periods, 2-3 days or longer. Two advantages: pails can be used instead of metal pots, and more importantly, wool won't shrink or felt up in cool water. Wool is easier to spin the less it felts but it is difficult to completely avoid with the heat method.
Take care not to heat wool and silk over 80C (180F). Wool felts up and silk loses its natural sheen.
Of the natural dye mordants, herbal mordant, tannin and alum are the most environmentally friendly. Copper with acetic acid is also commonly used for wool to give an even wider range of colours. Iron is often used as an after-mordant (ie. 2% iron added to used dyebath, then material returned to bath, simmered 5 minutes and left to cool). Tin and chrome are the most toxic mordants and avoided by many dyers. Chrome is not an historical mordant and didn't come into use until the mid nineteenth century.
Cellulose fibers, ie. cotton, linen, hemp, don't take up natural dyes as easily as wool and silk. They dye best if mordanted first in tannic acid, rinsed, then mordanted again using alum. Or even a three step process – tannin, alum, tannin.
See Natural Dye
Page for more information on all mordants.
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