Are these yarns color fast?
Yes! You'll be glad to know that natural dyes are just as colorfast as synthetic based dye. Natural dyes have been around since 2600BC or even before! The initial step in the dye process involves mordanting the yarn with alum which when combined with the heating process makes the dyes bond to the fibers permanently. Certain goods are tried and true and better for dyeing for that reason (indigo, madder root, cochineal) and others are not. Some materials have natural tannins and do not require mordanting, though I mordant anyway just to be safe. Some materials are beautiful but need a post bath in iron to fix the color. Beets, seem like they would be great, they certainly stain your hands right?! But I have read that they will fade away to white eventually, so I haven't even attempted to use it. I have taken great care to research the dye stuffs I find before I use them and will not bother to use dye materials that are not colorfast. Who wants to spend all that time and effort on something that will just fade away?! Not me!
All fibers are rinsed at least 2 times, washed and rinsed again as well to ensure that the color you fall in love with is the color you will have after many uses. As with any hand dyed yarn, with some darker more intense colors, some bleeding is expected for the first couple washes.
All dyed materials (natural or synthetic) eventually fade if they are left in the sun for long periods of time.