Sometimes, you need to hem something so it won’t show through from the front. In a perfect world, you’re working with two layers of fabric. But what happens if, oh, I dunno, you’ve got yourself a crazy corset that’s mostly lined, except for the gussets? Then you need to know how to blind-hem with only a single layer of fabric.
Fabric choice is kinda key, here. I’m using a sateen, which, like satin, has fairly long surface carry-threads. It’s still possible to do this with a plain-weave fabric, but infinitely more tedious. Here’s the trick:
I should probably mention that I have a major advantage with teensy0tiny stitches like this. My mutant super-power is micro-scopic vision. Like Scott Summers, I wear glasses to shield the world from my powers. When I take them off to do handwork, that 20/500 prescription suddenly turns into a killer advantage… ;)