Decolourant discharge paste not working on silk?
  • I painted your Decolourant on a test piece of silk habotai hoping to get noticeably lighter shades where the discharge paste was applied. I let it dry overnight and then ironed it with a hot steam iron set to the "silk" setting. Nothing happened. I applied heat for quite a while; I raised the temp and still nothing... The Decolourant was a new unopened bottle that I purchased 4-5 months ago.
    I originally dyed the silk with plant dyes as well as a little indigo and was hoping to apply some discharge prints/brush marks to create some interest on the overly dark scarf. Did I do something wrong? Thanks.
  • Hello,

    Unfortunately, discharge chemicals do not work on all dyes equally or even at all. Indigo is a known dye that the deColourant will not work on. It is due to the chemistry. The same chemistry that makes the indigo green in the bath is what allows the deColourant to work, so Indigo is no go with deColourant.

    The other natural dye I do not know what it is made from. Is it possible it is a pigment dye? Did you use alum to fix it? Does it bleach in the sun? If it is a pigment, it will not work. If it bleaches out in the sun over time, it may work.

    deColourant works best on reds, blacks, and browns. It will in fact work on turquoise procion which was a surprise to me.

    I don't think you did anything wrong, you just happened to choose an outlier that happens not work for your first try.
  • Thanks. Plant dyes and prints are quite subject to light fading which is why I thought Decolourant would work. I used vinegar to lower the pH but did not use alum or any other mordant.
    Do you have another discharge option? Can't use bleach on silk or wool.
  • Yes, this is the trouble. Bleach is still the strongest discharge chemical, but it does not leave the fabric untouched.

    There is zinc Formaldehyde sulfoxylate, which is stronger reducing agent. It is not stable in solution, so it will not last as a paste like deColourant, but it can be applied in sodium alginate or another thickener and is heat activated as well. It is nastier stuff than deColourant, but might work.
  • OK, I'll save the deColourant for cotton/plant fibers then.
    The two discharge chemicals I found to work decently on wool/silk are thiourea dioxide (thiox) and sodium hydrosulfite (Rit Color remover). I didn't use them for this application because I didn't know how to thicken them for application with a brush or as a print. What would I use as a thickener?
  • You can thicken them with Sodium Alginate if you want. It is just a smooth nice gel that can carry whatever you want. So, you can thicken it up and add the thiox or color remover in whatever concentration you want.