I have tried color catchers, but they can’t handle the intense concentration of left over dye in some yarns. I realize now that I need to check all my yarn before I knit color work. You might even consider testing your single colored projects since any color can fade with time. I wish I had checked my cardigan knit from Malabrigo Rios in the Archangel color way. I feel a little sad when I see fresh balls of this yarn and notice how pale my sweater has become over time. If you feel resistance to trying this process, think about how many hours you will spend knitting a project, and then all the years you will wear it, and then how many times you will wash it. I’m active, messy person and I wear my sweaters constantly. They need to be washed a couple of times a year, and I can’t afford to get them dry cleaned, so any effort to extend their life is worthwhile.
To test for colorfastness, I place about a yard of yarn in very hot soapy water to see if it changes color. All of the yarns in the quadrant above bled a little, but the black yarn was like ink. I washed all the yarn with a little shampoo and water and I tried purl soho’s recommendations for fixing dye with amazing results. You can see how much the black dye bled in the upper right hand corner, but the dye bonded completely to the yarn after I added the citric acid mixture. The yarn was dry in less than an hour thanks to my trusty food dehydrator. Please note that these tips are for acid based dyes and wool. Natural dyes and cellulose fibers will need different treatment to prevent bleeding. If you sew ribbon on your cardigans, may also be prone to bleeding. I recommend pairing ribbon with a similar or darker colored yarn so you can’t tell if the color transfers on to the sweater.