This is a really nice looking edge finish. It’s decorative and fully sealed. It shows up all throughout the ages – sixteenth century ruffs, smocks and chemises of all eras, even on modern blankets (of all things). It’s also a great utility stitch – milliners use it to whip wire down to buckram hat brims.
You will need an edge, trimmed down to a 1/8" seam allowance. I usually run a line of machine stitch just past the seam allowance line- it helps stabilize the edge as I'm working with it.
You will need some form of thread. I'm using silk embroidery floss. The color is lamentable, but it's the only thing I have in silk that's not white.
Fold your prepared edge under 1/8". (Your machine stitches, if you used them, should be hiding inside the garment now.) Push the needle up through the right side of the fabric.
Take the needle back over the edge of the fabric and push it up to the top, right next to your original stitch.
Make sure that the tail of the thread is behind and to the working side (left, in this case, as I sew left to right) or the needle. Pull your stitch through.
Take the needle back over the edge of the fabric. Push it up about 1/8" from the original stitch. Once again, make sure that your thread tail is behind and to the working side of the needle.
Lather, rinse, and repeat along your edge....
Continue until your last stitch butts up to your first (on a closed hem) or until you run out of hemming to do.
To finish, secure the blanket stitch by taking a short stitch right above your last stitch. This prevents the last stitch from going diagonal. Tie off on the back side of your work.
For a decorative look, you can place little bullion knots in between the lines of the blanket stitches. Here, you can see that the blanket stitch covers the raw edge of the hem inside, thus keeping the threads of the fabric out of trouble.
Here, I've used two rows of blanket stitching. The first goes over the edge and seals the hem. The second butts up to the first and is purely decorative. Combined, they give me a wider border, which is rather nice.
Incidentally, if you think that this looks exactly like the stitch you’d use to bind an eyelet, you’re correct. The only substantial difference between the blanket stitch and a simple buttonhole stitch is size – buttonhole stitches are closer together.