In my last post, I didn't think you could shorten a metal zipper. When you shorten a nylon zipper, you are left with teeth, which are fine to sew over, unless they are big chunky ones like in a separating zipper. You certainly don't want to be sewing over metal zipper teeth. Anyway, since the obstacle here is actually just a few zipper teeth, we just need to get rid of the teeth. Oh, and move the little stoppers that stop the zipper head from sliding off your zipper. We don't want that to happen. That might make us jump up and down and swear. A lot.
Some useful tools are some wire cutters. Now, I tried using my cute little pink ones that I have for jewellry making (ah yes, of course I've tried jewelry making, I try everything, remember), but they just didn't cut it. So I
Also, you should wear some eye protection. You might be able to have more control over the little zipper teeth, but when I did it, there were shards of metal flying everywhere. Since we don't want sharp pieces of metal in our eyes, put some safety specs on.
Also, put some safety specs on anyone else that is around, or even better, send them out of the room, because they might be distracting and touch things they aren't supposed to.
Just because I'm a little concerned that someone might zip my zipper head off during the process, I popped this safety pin on. To avoid potential swearing.
Anyway, the idea is, you snip off those zipper teeth using the wire cutters without cutting the fabric of the zip. Try to imagine that the teeth are sort of U shaped with the top bits of the U really close together, pinching the zipper tape. If you just snip off a part of that, right through the metal, the rest of the tooth will just pull right off. You need to measure the number of cm that you need to shorten the zipper by and remove the same number of teeth from each side of the zipper.
Measure from inside the stopper, not outside, or you will end up with a slightly longer-than-necessary zip. My zipper originally measured 13cm, and I needed an 8cm zip, so I removed 5cm worth of zipper teeth, or 20 teeth from each side.
Without breaking them, you need to prise off the metal stoppers and pop them down near the last zipper teeth. Squeeze them back together, and check to make sure they are secure. Chop the excess zipper tape off, using pinking shears and another jeans zipper as a guide. If you don't have another jeans zipper to guide you, mine measured about three and a half cms from stopper to end. Just going by the zips in my stash, jeans zippers have more tape beyond the top of their teeth than dress zippers do.
Voila! A shorter zip!