This is a very small skein of commercially spun 10/2 bombyx silk noil yarn that I dyed at my class over the weekend. It reminds me of kelp, so I'm calling the colorway Kelp. Believe it or not, I have virtually no experience dyeing yarn! I've always dyed my fiber first and then spun it. So with my success here, I now have ideas in mind for dyeing yarn that I've already spun.
You get a very different end product when you dye first, then spin than you do when you spin first, then dye. In the first case, the colors tend to be spread more evenly throughout the yarn resulting in a more heathered look. This can be avoided, depending on how you strip the dyed roving or top before it's spun. But that seems to add a level of regimentation to the spinning that I don't care for.
When you spin first, then dye, you get more distinct color areas on the yarn. Most sock yarns are dyed this way, so when they're knit up, you get chunks of colors throughout the finished piece rather than an overall heathery look.
I'm still under the weather today, headachy and low energy, but I had to have a burst of color to brighten up my spirits.