Wool/Cotton yarn?
  • I am delighted to have found this forum!

    I want to dye off-white yarn that is a 50/50 blend of wool and cotton. All the research seems to indicate a different dye and process for each fiber. Is there a way to do this in one process? I only want a solid color.

    Cheers!
  • Ladyhawke said:
    I want to dye off-white yarn that is a 50/50 blend of wool and cotton. All the research seems to indicate a different dye and process for each fiber. Is there a way to do this in one process? I only want a solid color.
    Much as we dyers like to warn against the use of all purpose dyes, due to their poor washfastness and relatively poor performance on cotton, this is the perfect application for them. All-purpose dyes contain a combination of direct dye, which is a hot water dye that works on cotton, and leveling acid dye, which works well on wool, although it is less washfast than other classes of acid dye. You can apply both dyes at the same time, heating your dyebath to a simmer (just under boiling temperature), with salt and either vinegar or another acid. Packaged all-purpose dye mixtures contain salt already; I don't know if they also contain acid. If the washfastness is not adequate for you, you can apply a cationic dye fixative such as Retayne, but be aware that doing so may reduce lightfastness.

    You can dye both the cotton and the wool with fiber reactive dyes such as Procion MX dyes. I have read that this should be a two-step procedure, one step with soda ash since the cotton requires a high pH to react with Procion MX, and one step with acid so that the Procion MX dye can act at low pH as an acid dye on the wool. (Add sufficient acid to neutralize the soda ash in the first step, and then add more, to bring the pH down to the usual level for dyeing wool.) However, I have found that the wool in my test swatches, at least, does take some of the Procion MX dye even at high pHs. You must avoid using the usual high pH of 10.5 to 11 that is normally used to dye cotton with Procion MX dyes, because it is damaging to the wool. You will need to compromise between the ideal pH for the cotton and the ideal pH for protecting the wool. Procion MX dyes will work on cotton at a pH of 9 or even 8, though you may notice a loss of efficiency. It's worth it to protect the texture of the wool. (No dyeing at all occurs on cotton at a neutral pH of 7, or below.)

    To reach this compromise pH level of around 9, it is not enough to just use less soda ash than you usually use for cotton, because even a low concentration of soda ash in water will produce a pH around 11; to attain a moderately elevated ph, you will need to combine soda ash and baking soda. Use pH paper to check the results of a particular ratio; it may vary a bit depending on your water supply (I'm not sure about this). Baking soda alone will produce a pH around 8, if I recall correctly.

    Paula