TL;DR version: make sure your hooks and eyes are face to face with the outside of your fabric and are lined up so the hook and eye parts are *not* on the seam allowance side.
I’ve not yet seen any tutorials on hook and eye tape that really explains how it works, of course you can always choose to have the tape exposed or use them a different way but I hope that this can help somewhat as I spent my first go at using the stuff really nor sure why there was fabric on both sides of each tape… they were sold separately by the length and no instructions!
Hook and eye tape is sewn in two lengths, the loops of each hidden inside the tape and machined in place.
Here you can see that there is a wider side and a narrower side. The wider side is the side used to secure the tape to the fabric and the narrow side is used as a sort of placket- to protect the skin or inner layers from the metal pieces. You can choose to have the placket either side, I use it behind the loops so as to make it easier to hook the hooks through the eyes- if reversed you will need to work the loops between fabric and hooks and it is not that easy!
I usually do the loops first, I lay them down down face to face with the fabric, widest strip lined up with the edge of the seam allowance. And then sew as close to the stitch lines already present in the tape. The eyes will be on the body side of the seam, the loops to hold the eyes in place will be on the seam allowance side.
CAUTION! Go slow as the wire loops are in there and you do not want the needle to hit any! I have used hand sewing to illustrate this step as it may be the safer option.
If you sew by machine this side is okay to use with a normal foot. So long as you can follow the stitch lines. And keep an eye open for the loops!
Then turn the tape and seam allowance back on to the lining and stitch in place, I use a whip stitch usually. Here the placket is on the left and the seam allowance on the right. The velveteen shell fabric happens to be pushed aside however you can sew through all layers or just catch the outer shell depending on your preference.
It is also possible to topstitch- the velveteen below is the correct side of the skirt- the seam allowance folded under. This is very strong and holds the loops in place yet again. But again CAUTION as the wires are hard and can damage or break a machine needle.
The hook side is a little more tricky. Lay the tape face to face with the fabric this time with the narrow strip along the edge of the seam allowance. The hooks will be on the opposite side of the stitch line.
I have the photos below oriented so that the skirt fabric/tape will mirror the loop side of the opening. This is fine for hand sewing (again follow the stitch lines) but for machining you will want to have the seam allowances on the inside of the machine. This is where you will also want to use a piping foot. The hooks are more raised than the loops so will not be easy to machine over with a normal sewing foot. The closer you can get to the stitch line the better but CAUTION the hooks are metal and will break your needle if you hit them.
Turn the tape and seam allowance open and then towards the lining fabric.
Again it is possible to whip stitch the tape on the lining or you can topstitch by hand or from the lining side- again using a piping foot as CAUTION the hooks are still there! Still being all metal and stuff.
And this is what it should look like in the end.
It is also possible to sew a lining to obscure the tape, here I have hidden the loops of hand set hooks and eyes but the idea is similar.