Even though we have a zip in the lycra suit, a zip is also necessary in the back of the latex suit. For this I use a heavy duty zip just as with the back of the mask.
To sew it in, the easiest way is to make thin strips of the latex fabric and attach the zip to them, zince the latex is quite hard to sew in, especially a zip that should be durable and needs to be correctly sewed in.
I use the thin zip foot in my machine, with the needle as far to the edge as possible, this to get close to the zip. I then secure the zip with a zig zag about 1 cm in from the edge. You need to remember to use leather point needles in the machine, since it is the best one to cut through the latex, I have tried a bunch of different ones.
You then apply the strips with latex to the suit it the back and sew it in on top of the latex suit, this makes the zip perfect and it also increases the strength to the back bit that will be pulled and stretched a lot when getting dressed.
It is important to remember not to make the costume bigger, don't add anything to the size, simply attach it on top allowing the zip to lie on the edge. I sew it on by hand, and then on the machine using zig zag. Then I simply blend the strips in with the rest of the suit using latex.
To cover the zip in the back I att a long piece of the latex skin on top of it, attaching it to one side of the zip with brushed on latex.
I then blend it in with more brushing latex, and the result is that you no longer will see the zip, if you dont look for it.