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Wednesday, July 8, 2026

Dye Project: Preparing Protein Fabric (Scour & Mordant)

I like to have a batch of prepared fabric on hand, so that when I come across an interesting dye source I'm ready to dye. The process involves scouring the fabric to remove impurities, mordanting the fabric so the dye bonds with it, and optionally brightening or saddening the fabric to intensify or modify color and improve its fastness. Last year I documented how to prepare a batch of plant-based fiber, such as cotton and linen, to have on hand (see Dye Project: Preparing your Fabric (Scour, Mordant, Brighten or Sadden).

This year I'm documenting how to prepare a batch of protein-based fiber, such as silk and wool, for a series of projects. The process for preparing protein fabrics is similar to the process used for plant-based fibers. The exception is that wool and silk do not respond well to extreme changes in temperature. For best results, keep it slow and steady when bringing the bath to temperature and cooling it.


Silk scarves - scoured and mordanted


I summarized the process of scouring and mordanting silk briefly back in 2022 in Dye Project: Eco-dyeing Spring Flowers and Plants, by saying that "the fabric was scoured with Orvus paste and soda ash, and mordanted with gallnut" and promising a separate video. I hope to finally fulfill my intentions to record the process in this post.

For this project, I'll be preparing an assortment of protein-based fabrics, including six silk scarves (100%), a couple of silk and wool blend scarves (63% and 37% respectively), and a silk velvet and rayon blend scarf (18% and 82% respectively). I obtained all of the scarves from Dharma Trading. I also have a leftover silk scarf that was prepared in 2022. It does not need to be re-scoured or mordanted, but it will be interesting to see if four years has an impact on the color or light fastness of the material.


Scarf: silk (screenshot from Dharma Trading website)

Scarf: silk/wool blend (screenshot from Dharma Trading website)

Scarf: silk-velvet with rayon background - Leaf2 pattern
(screenshot from Dharma Trading website)


Scouring (Orvus Paste)

Purpose: Scour silk fabric to remove impurities that may compromise dye results. According to the website, silk scarves from Dharma do not need to be scoured, but I'm doing it anyway to be sure. These instructions are based on the process recommended by Maiwa Textiles, which is to use Orvus paste to remove any remains of lanolin or other impurities from the silk fabric (this time I'm not using soda ash with the Orvus paste). Orvus paste has a pH of 7.8 (slightly base). I plan to scour the silk and silk-wool and silk-velvet rayon blends together, as demonstrated by Maiwa.

The basic process for this step:

  1. Before you start, weigh the dry fabric and record this value as the Weight of Fabric (WOF).
  2. Prewash the fabric in the washing machine, using a textile detergent.
  3. Scour the fabric in heated water, using Orvus paste (sometimes called "horse shampoo" or "quilt soap"). 
  4. Let the fabric cool down, and then rinse.


Orvus paste, a.k.a., "horse shampoo" or "quilt soap"
(screenshot from Amazon website)


For scouring a pound of fabric, use:

  • 1 teaspoon Orvus Paste 

For example, I plan to process 7 ounces of silk and silk blend (almost half a pound, or about 200 grams), so I will use 1/2 teaspoon of Orvus paste.


Scouring protein-based fabric with Orvus paste


Scour the silk fabric:

  1. Pre-wash the fabric in the washing machine using 1 teaspoon of textile detergent, such as Synthrapol or Professional Textile Detergent. Hang to dry and process later, or use the damp fabric in the next steps.
  2. In a large stainless steel pot, add Orvus paste to about three gallons of water and stir to mix. The pH registers at 5 (moderately acid).
  3. Add the damp fabric to the pot and distribute it so that the fabric is not crowded. Add more water if needed to cover the fabric.
  4. Heat the water to 140 ℉ (60 ℃), stirring periodically to rotate the fabric. Unlike my experience with scouring plant-based fabrics, the silk and silk blend fabrics did not turn brown with impurities.
  5. Maintain the temperature for an hour, periodically stirring the fabric gently to rotate it. After an hour, turn off the heat, and let the water cool down.
  6. Remove the fabric from the scouring bath. Rinse it in cool water, and squeeze out excess water. Wash the fabric in the washing machine (cool water, no detergent). Optionally add an extra rinse cycle.
  7. At this point you can immerse the wet fabric into your mordant, brightener, or dye bath; or you can air-dry the fabric and store it until needed. Label it so you know that it was scoured.


Rinsing the scoured protein-based fabric


Mordanting (Alum Sulfate)

Purpose: Mordant the scoured protein fabric to prepare it to receive and hold dye. Multiple mordants are available, but here I am using alum sulfate. Optionally I could add cream of tartar for the wool, but cream of tartar is not typically used for silk. Since I'm processing them together, I have chosen not to include cream of tartar. Again, these instructions are based on the process recommended by Maiwa Textiles.


Mordanting the protein-based fabric with alum


Mordant the silk fabric:

  1. Prepare a large stainless steel mordant pot by filling it with enough warm water (110º F, or 45º C) to cover the fabric when added, usually a 30:1 ratio of water to fabric.
  2. To a small non-reactive container, measure alum at 15% WOF (I'm using 2-3 tablespoons, or about 30-40 grams) Optionally, I could add cream of tartar for the wool at 6% WOF (about 3 to 3.5 teaspoons, or about 12-13 grams). Cream of tartar is not necessary for the silk, so I'll omit it this time; but it wouldn't hurt the silk in a mixed batch, so I may try adding it in a future project.
  3. Add very hot water to the container, and stir to dissolve the alum (and the optional cream of tartar).
  4. Pour the dissolved alum solution into the large stainless steel pot of water, and stir well. The pH registers at 3 (still moderately acid, but moving toward strongly acid).
  5. Add the scoured, wet fiber. Over 30-45 minutes bring the temperature up to 160-180 ºF (70-80 º C).
  6. Simmer the silk fabric at 160-180 ºF (70-80 ºC) for one hour. Stir the fabric regularly with a stainless steel spoon so the alum is evenly distributed.
  7. Let the mordant bath cool for 20 minutes.
  8. Remove the fabric from the mordant bath. Rinse well in cool water, or wash the fabric in the washing machine (cool water, no detergent), with an optional extra rinse cycle. You can store the fabric in a damp white cloth for 24-48 hours (keeping it damp during this entire period), and dye it in the next day or two. Or you can air-dry the fabric and store it until needed.
  9. Once completely dry, the mordanted fabric may be stored indefinitely. 


Drip drying protein-based fabric


Ready to Dye

At this point, your silk fabric is scoured, mordanted, and ready to dye. Having a stash of prepared fabric is like having a full pantry that is available when you're ready to cook up a storm. I'm planning to use this batch for several dye projects that use mushrooms,


Prepared protein-based fabric labeled and ready to dye!


Mordanting Additives

When you are ready to dye, you can add additional mordants to the dye bath to further manipulate the dye. For example, you can add more alum to brighten the dye bath or ferrous sulfate to sadden, or darken it. You can add vinegar to make the dye path more acidic, or soda ash or ammonia to make it more alkaline. You can add titanium oxalate to push the dye to a more golden or orange color. Experimenting is part of the fun of dyeing! 


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