Isn't the zipper going to be on the top.If so the only thing that should be even close to where you serge will be the ends of the zipper tape(none metal,zipper part).Just remember to open the zipper before you sew up those side seams. Oh never mind you said you'll be serging on the right side,is that correct???
Kathi

Yes, I will be serging on the outside. I was thinking that the zipper will be across the entire top and that in order to serge the sides I'll have to serge across the teeth. I should say that the one I'm practicing on ,I've shortened so you really do have to serge across the teeth.Am I making sense? ummm...I wonder what the shortest size zipper I can buy is ...anyone know?

You can get 6 or 9 inch zippers I think. I would think it would damage your blades to serge over the teeth, or it could make the machine jump time.
Susan

I must be having a DUH moment,cause for the life of me,i can't see why you would have to serge over the teeth.Put the zipper in using your regular machine,actually it doesn't take that long to do the whole thing on a regular sewing machine.
Kathi

You can get 4 and 6 inch zippers. I would go with a longer zipper, the 9" for the simple fact that makeup pencils and crayons will fit better and not break in longer bags.

What is the difference between serging it wrong side together versus right sides together, serging that way, and turning them out? Secondly after you put the zipper in, you trim the zipper tabs so you won't have to sew over the tabs and a lot of unnecessary bulk. I just checked one of mine, and that is how it is sewn.