So you think you have found a bleeder!
Bleeding yarn is the bane of every dyers life and happens with the most experienced indie dyers and even happens with commercially dyed yarn.
The science of dyeing:
I don't want to go into technical process but acid dyes might sound scary and nasty but the acid side of the process can be from vinegar or citric acid.
I use food grade citric acid, (used to make sweets sour) along with heat sets the dyes to the yarn.
Swatch Swatch Swatch:
My honest recommendation when using hand dyed yarn in your projects is to swatch, for obvious gauge reasons but also to check for any bleeding or staining.
So your yarn is bleeding:
If you have carried out a swatch and noticed that the yarn is bleeding.
Still in hank form, add one big figure of eight tie in the middle. Give the yarn a wash in the same way you would wash your FO. Bear in mind that I don't use wool wash so whilst the yarn will rinse clear for me with just water, the wool wash you use may leech out some colour, I don't recommend using them. Blue dye molecules are slightly bigger than any other colour and are more likely to contribute to bleeding.
The colour of the yarn doesn't change but the yarns still bleeding:
This is because the dye has been set correctly on the yarn but has either not been rinsed properly or your water is too hot or you're using a wool wash that is leeching out the colour. Just keep washing and rinsing to remove the excess dye. If the colour of the yarn is changing, or fading, that means the dye has not been set properly at all. If the colour is staying the same, you don't need to reset it, it's just excess dye that is coming away. Fibre can only hold so much dye.
One thing to bear in mind is that the composition of the water that I rinse the yarn with may be different from the water that you use, i.e. slightly different pH level, hard water v soft water, presence of added chemicals such as fluoride. Whilst I can try to ensure that yarn and fibre will not bleed in my water conditions, I am unable to give that guarantee to your own water conditions. It's all chemistry.
How do I set the dye?
With your yarn in a hank soak the yarn in citric acid or vinegar ensuring its completely saturated, wrap in cling film and place in a pan with a vegetable steamer, leave for 30 minute and allow to cool completely, rinse and check for any bleeding
With FO you will need a large stainless steal pan that you will never use for cooking again, ensue there is enough room for the FO, Add the citric acid or vinegar with cold tap water, place in the FO and Slowly heat the pan for about 30 minutes and occasionally stir gently. Very gently, especially if the yarn is not superwash. You don't want to boil the water but you want to get it simmering. Take the pan off the heat, put the lid on and let it cool. The water should be completely clear the next morning, meaning the dye molecules should have bonded to the yarn. Set the dye slowly, there's no rush. I'm of the opinion that dyeing should be a slow process, just like knitting. Try using a colour catcher when washing if you have used different colours but it is always best to check for bleeding before you commence your project.
There is dye all over my hands!
This is called Crocking. It's the same thing as buying dark colour jeans and it has a tag that warns about dye transfer. Crocking is generally caused by the pH value of your skin pulling out the dye molecules. It doesn't mean that the yarn will bleed though once it hits water, I mean it might, but it doesn't mean that it definitely will. I find that this is more likely to happen with colours that use blue dyes and/or yarns made from non superwash wool and silk.