Such a good choice to transform your knitting into a hairband (not sure which kind of weather you have right now, but here its getting cold and hair bands and hats are coming out). I love the neat garter stitch on this project and I think it will be comfortable to wear as it has a bit more stretch than stockinette. And yes to the problematic black. I also like it a lot as a color, but knitting with dark colors especially in the vending is tough. I always have problems to identify the stitches (I started on a new pair of striped socks and one color is a dark brown 😱)