17 May 2009

Scouring fibers is the process of removing waxes, oils, dirt, finishes and anything else that can interfere with dye uptake.  Scouring is the most important step to good dyeing.  If there are blotches of oils or perspiration in the fibers the dye will be a different color in those areas.  At the end of the scouring process the fiber should be free of interfering chemicals and nearly white.  Fibers in this condition are called Prepared For Dyeing or PFD.

Think of scouring as a vigorous washing that removes all contaminates and leaves behind no residue.  You can do it yourself or you can have some one else do it.

I could write a lot about scouring and still not cover your situation, so I’m going to try to keep it simple for beginning dyers.

1.    You can just wash your yarn and hope it works.  This works 80%  of the time with purchased white or natural yarn.
2.    You can buy yarn that is PFD.
3.    You can do a true scour, this is best when you know or suspect the yarn is dirty.

After you have made your yarn into a skein and secured it with many loose figure eight ties you can wash it.  The choice of detergent is important here; home laundry detergents can have bluing, optical whiteners and  perfume that they leave behind to interfere with the dyeing. We have specialized detergents for this: Synthrapol and Orvus Paste (you can get a small amount of these from me). Otherwise choose the simplest detergent you can get your hands on; no perfumes, should be colorless to pale yellow- baby shampoo for example.  Wash in hot water with a bit of detergent.  If you see dirt come out into the wash water, wash again.  Rinse 3-5 times to make sure all the detergent is gone. Wring.  No need to dry before dyeing, this first step of dyeing is to wet out the fiber.

You can buy fibers that are commercially scoured or scoured and bleached that are labeled PFD.  These should be fine if they have not been soiled waiting for dyeing. Buying PFD is a time and hassle saver.

You can buy yarn that is ready to dye from your local hand-spinner.  She usually has cleaned the wool before spinning and she can tell you exactly what she did and how much lanolin is left in the wool.  Tell her you want to dye it  and does she think it needs to be washed again?

I know of two manufactures that make a wide range of PFD yarns that are available in many retail stores: Henry’s Attic ( most of their yarns are PFD) and Brown Sheep Company (avoid the Superwash wool and colored yarns). Visit their websites to find a retailer near you.  There are other sources too, but maybe have a more limited range.  White spun silk yarns are usually PFD as are white or natural perle cottons. The rayons and other regenerated cellulose fibers such as Tencel, bamboo, soy silk etc. are pretty clean  because of the manufacturing process.  I also have some extra PDF yarns I know dye well that you can buy, including Henry’s Attic Coconut Silk (a textured silk/wool yarn), call if you want to see what I have.

The scouring process differs by what you are trying to remove.  Cotton comes with naturally occurring waxes and pectins that are difficult to remove. Wool comes with vegetable matter, burrs and such that get caught in the fleece, and lanolin produced by the animal. Reeled silk has both the silk fiber, fibroin, and the gum, sericin.  The sericin has been removed in spun yarn and all supple silk yarns. Tussah silk and linen are challenging to prepare for dyeing.

Commercial yarns may be bleached, or have bluing or optical whiteners added, all  to make them appear whiter.  Any chemicals or residue left in the yarn can interfere with dyeing. Finishes, wash-and-wear, wrinkle resistant, mercerized, singed, flame retardant, water repellent, water proof, antistatic finish, peach finish and stain resistant, can be a problem. Some  of these, the wash-n-wear, wrinkle and stain resistant ones,  are a plastic or resin type coating on the fibers and are quite effective at blocking the dye from penetrating the fibers.  I find it best to avoid  these finishes.  Other process, mercerizing, singeing, degumming, pre-shrinking , do not leave chemicals behind to block the dye penetration but they do effect the color.  Mercerized cotton  will dye a much more brilliant, lustrous color than the same cotton unmercerized.  Degummed silk will dye lighter than the same silk with the gum; the gum is a protein too and also dyes with the protein silk fiber.

Hand-spinners deal with cleaning fibers and getting it ready for spinning and are a great source of information. The more you know about what you are trying to remove the easier it will be.  

Here is a general scour process:
•    Soak the yarn in water to cover for 30 min. or more.
•    Use a dyepot for the actual scour.
•    Add 1 or 2 gallons of water, enough to cover the yarn and allow it to move freely in the bath.
•    Add 1 Tbsp. soda ash and ½ tsp. Synthrapol for each gallon of water.
•    Add yarn and heat to boiling. Move the yarn gently in the bath so that all parts of the yarn are exposed to the hot bath.
•    Simmer 10 min. for wool and 30 min. for cotton.
•    Remove cotton from the hot bath. To avoid felting wool, allow it to cool to warm and remove to a rinse that is the same warm temperature.
•    Rinse the yarn 3-5 times.  Cotton can be wrung and is ready for use.  Wool needs a 20 min. soak in a vinegar bath (1Tbsp. white vinegar per gallon) then wrung.

No need to dry before dyeing, this first step of dyeing is to wet out the fiber.
If you have questions feel free to contact me directly.


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