I first came across a concealed hook and eye in a Prada shop in Las Vegas. I went in with the sole intention of poking around their dresses and seeing if there was anything I could learn from their construction. I did!
To insert your own concealed hook and eye is really not difficult at all. You just need to re-order your mental step-by-step process. Sewing on the hook and eye is not the last thing you do. It’s a ‘during construction’ step.
Above is a during construction shot of the back bodice of my Anna Dress. The invisible zip has been inserted and the neckline facings still haven’t been tacked down to the zip. Can you see the tops of the zip, where the teeth end? They haven’t been sewn down and I’m going to fold them out of the way at a 45 degree angle as on the left. Above them, I’ll insert my hook and/or eye.
I use a pin to keep the top of the zip out of the way and hand sew the hook or eye in place. I’m careful that my stitches don’t go through the main body of the dress. I’m sewing the eye to the seam allowance only. A few stitches in both loops should do it; I don’t go mad.
Then I fold my facing over to the inside of the dress, turn in the seam allowance, and sew the facing down to the zip, going over the eye. Voila! No scrappy bits of hand stitching on show, no hook and eye interfering with the lie of the neckline, and secure as can be in their little hand sewn beds. Aw, bless.