These leggings are cut from thick cotton knit with tons of stretch. I dyed them with Pro Chem MX Fiber Reactive dye.
I serged the leggings first with white thread, then garment dyed them in an intense bath of golden yellow plus a little purple in our old toploader. The fabric did not take the dye as well as I hoped. I performed the waistband stitching with matching thread last -- the thread I use does not take the dye at all.
On super cold days I will stay toasty in these with thermal tights underneath. Everyone needs stretchy pants. And I will be able to pretend I am a bird in my stretchy pants.