Dyeing in the Fabric
A technique that is currently creating excitement in knitting circles is dyeing in the fabric. A square is knitted, dyed then unravelled and reknitted. Unlike dyeing a skein, this produces a yarn with longer repeats of color, which means in turn that a single color can circle the circumference of a sweater or sock many times before merging into a new color or shade. Using this method, you can knit a Fair Isle sweater without disrupting the flow of hand knitting with frequent yarn changes and without having to endure the tedium of securing the ends of separately dyed skeins of yarn.
Pro Chem has a good website with instructions for using each kind of dye and textile paint, including directions for painting fabric or warps: www.prochemical.com. Or look up Dharma Trading at www.dharmatrading.com.
Protein fibres (wool, silk, alpaca) are best used with dyes formulated for them eg acid dyes and natural dyes. Cellulose fibres (cotton, rayon, linen, Tencel) have different requirements. Not only are the dyes different, but also the treatment and mordants. You can use a fibre reactive dye for cellulose fibres. These work at room temperature and do not need to be heat set. Margaret Coe wrote in a recent discussion on WeaveTech:
There seems to be a bit of confusion about dyes so it's time to drag out the soap box. The pigments in dyes, acrylic, water color and oil paints, and even food are frequently the same. It's the method of attaching the pigment that differentiates the products.For protein fibres the pigments are formulated into dye that attaches to the fibre using acid. For home studios these are frequently in the "weak acid leveling" category, though the popular Sabraset/Lanaset are 1:2 metal complex reactive dyes. Acid dyes give good light and wash-fastness and brilliant color on animal fibres such as wool/silk and nylon, and are applied at boiling point. If you used vinegar the assumption was that you had used an acid dye. You do not want to use vinegar with a fibre reactive dye.
For cellulose fibres the pigments are formulated into a dye that attaches at a molecular level using alkali (the opposite of acid.) These dyes are called fibre reactive and give good light and wash-fastness on cotton, linen, and silk. Popular brands are Procion and Sabracon/Cibacron. Note that they "can" be used with wool, but they are not preferred. These dyes also hydrolyze, that is, they bond with water thus, in solution form, they have a limited shelf life. So with time, more dye is required to obtain depth of shade. To get deeper shades from fibre reactives use salt it's cheaper than dye.
Finally, the goal here is to obtain light and wash-fast colors on fibres, or it should be. A lot of methods proposed do not necessarily give you good results. They'll look okay initially, but in time will fade or, worse, bleed. And it is no more difficult to follow the correct procedures than the less than correct.
With all dye, to obtain the optimum light and wash-fastness an adherence to time and temperature requirements is needed. Procion MX is often referred to as a cold water dye, but it actually needs temperatures of at least 75 to 95 degrees, and does quite well at higher temperatures.
Sabraset/Cibacron requires temperatures of 105 or so. Both require that the fibres sit in the dye for a minimum of 1 hour to 24 hours at the required temperature.
If you are producing for your own consumption then it's your choice, but if you are producing for articles to be sold to the public it is crucial that you follow correct procedures.
Margaret Coe — (via WeaveTech Mailing List)