I am asked all the time about whether my yarns are color fast and wash fast. And my usual answer is yes. But I need to clarify that answer. And I’m going to try to not sound like too much of a chemistry geek, so here goes.
The dyes that are made to dye protein fibers are called acid dyes. There are many different formulations of these dyes but they all work the same way.
To be totally washfast, the dye molecules need to hold on to the fiber like you would hold onto your child on a busy street. You have a strong grip on your child and he or she won’t be able to get loose. But acid dyes don’t work that way. They have a very loose grip, more like holding someone’s hand with your pinkie. In the right conditions, that pinkie can slip away. Wool, silk, mohair and alpaca fibers hold the dye particles very weakly.
If you wash or rinse your yarn or your knitted garment in HOT water, the dye will fall off and you can have bleeding into other colors that are nearby. This is especially true with reds and turquoises.
If you are buying roving there is another layer to the story. With roving, dyers need to be very careful not to felt it when dyeing and rinsing, so there may be more loose dye particles in roving. When you are drafting and spinning your roving into yarn, you can be dislodging these tiny particles from the fiber and so when you rinse your yarn to set the twist you may have more dye run off. So be mindful of that. Again, rinse your newly spun yarn with cool or cold water.
Good dyeing technique makes sure all the dye in the pot is now on the yarn or fiber. It’s called exhausting the pot. Good dyeing technique makes sure that there is plenty of time for the dye to attach to the fiber at the correct temperature. And finally good dyeing technique makes sure that the yarn or fiber is rinsed and that the water from that rinsing is clear without any dye particles in it. And know that all my of yarn and fiber has gone through these 3 steps.
Now if you are spinning the roving and your hands are becoming pink or blue, that roving hasn’t been properly heat set and rinsed. That’s a bad dye job. If you get a roving like that I would urge you to wet the fiber, wrap it in plastic wrap or put it in a plastic bag and steam it for 10 minutes. Then you can let it cool and rinse it out. That should fix the problem and this should have been done by the dyer.
So how should you wash your garments or yarn? If you are making a fair isle or other colorwork item, rinse the yarn before you do all that knitting. You will be able to tell if the yarn will run and you will mitigate the problem before it is a problem. And each time you wash your hand knit or crocheted items, you should wash in cool or tepid water. Use a nice wool cleaner, I use The Laundress Wool and Cashmere Shampoo and then lay flat to dry.