How to Install A Zipper in a Garment Part One

I taught my zipper class in April. One of my blog readers was there and mentioned she didn't remember me doing a post on zippers. I think that means it's time for one. My samples use mismatched zippers and thread colours so students can see clearly what I've done. Even with the contrast you cannot see my hand stitches from the front. They are buried in between the first and second stitch of the garter border. As usual, I have far to much I want to share with you on this topic so this is Part One of a series. I'll start with some general information.

Using a zipper for a closure on a cardigan is a stylish alternative to buttons and buttonholes. Current fashions often use exposed zippers. This is a relatively modern trend to take the functional and use it as surface decoration. We tend to see zippers more often on men's sweaters. I think it's partially because the designs for men tend to be a little more streamlined. The only cardigan my husband ever purchased had a zipper because he though buttoned cardigans look too "grandpa".

A zipper works especially well for garments which lay flat against the body with no fold over at the neckline. Look for the separating type when purchasing a zipper for a cardigan.

The chain or teeth of a zipper may be manufactured from metal, moulded plastic or from a nylon coil. Metal versions can be found in several different finishes from aluminum to brass and oxidized black brass. The size of the chain teeth varies and is measured by gauge. The tape the chain is mounted on, changes size in relationship to the chain.

Zipper length is determined by the measurement from the bottom stopper to the top edge of the slider when the zipper is closed. The tape which extends beyond these two points is not included in the measurement.

Zipper tapes are most often made from polyester or nylon, but some cotton tapes are still available.

Sliders can vary in style, materials and colour. Sliders come in locking and non-locking versions. Locking sliders are made with a small pin that is inserted between the teeth on the zipper chain. This locking pin prevents the slider from moving down the zipper chain and opening the zipper, until the slider tab is pulled, which retracts the locking pin and enables the slider to move freely up and down the zipper chain. The pulls attached to the slider vary from functional to decorative versions.

Zipper length can be customized by the vendor or by the knitter, to shorten a zipper which is too long. The zipper stops at the top can be removed with pliers and repositioned or replaced with a thread stopper. The bottom of a closed zipper can be shortened by sewing across the teeth. Teeth can be removed from the tape with a small pair of wire clippers.

The main difficulties knitters have inserting zippers are due to the mix of a relatively stiff zipper tape with the fluidity of hand knitting. Cotton tapes are softer, synthetic fibre tapes are stiffer. 

Blocking must be completed before inserting a zipper to avoid any shrinking or loosening of the knitting once the zipper is sewn in. 

Zipper installation for hand knits is best done by hand as it allows for more control. The goal is to sew the zipper securely without creating any puckers or ripples in the hand knitting. Using a sewing machine is likely to distort the knitting due to the movement of the feed dogs pulling backwards on the zipper while the presser foot pushes the knitting forwards. The one exception is machines which have a walking foot.