One of our regular (and favorite!) customers, Sheri, came in to Purl the other day with an immaculately knit sweater in one hand and a ready-to-go zipper in the other. She was a little daunted, and no wonder - when it came time to sew in the zipper, her pattern instructed her to take everything to a tailor!
Instead of running to your nearest expert, why not become one yourself? Sewing in a zipper doesn't require an apprenticeship with an Italian suit maker, or some kind of fashion degree - it's easy!
This tutorial comes from the SNUGGLE SACK project and so uses a non-separating zipper, but the instructions are the same for a separating zipper. Also, this tutorial only deals with zippers that already fit the knit piece; it doesn't explain how to custom cut a zipper. Maybe next time!
Step 1: Block It
First, if you ever intend to wash or block project, you should do so now. This will prevent unexpected stretching or shrinking. Of course, let the project dry before you sew in the zipper...
Step 2: Pin the Zipper Into Place
With the zipper closed, pin it into place. Make sure the bottom and/or top of the zipper are where they are supposed to be. (In this case, the bottom of the zipper is tucked right into the bottom of the zipper opening.) Bring the edge of the knitting up close to the zipper but not so close that yarn will get caught in the teeth when you zip and unzip. Also, both the zipper and the fabric should be flat and relaxed; don't pull the fabric unnaturally or allow it to pucker between pins.
Step 3: Sew the Zipper
With a sewing needle and thread the same color as the yarn, back stitch the zipper into place. Working with the right side facing you, sew in a straight line, following the column of stitches just next to the edge of the knitting. I started at the bottom of the zipper and worked my way to the top, but unless you're custom cutting a zipper, it doesn't really matter.
Here's what the knitting looks like all sewn to the zipper.
Step 4: Repeat Steps 2 and 3
Pin the other side of the zipper into place (including the bottom, if you're using a non-separating zipper).
Sew this side of the zipper the same way you did the other side. (Sew across the bottom too, if you're using a non-separating zipper.)
Step 5: Baste the Inside of the Zipper
Turn your project inside out, so the wrong side is facing you.
Fold the excess fabric from the top of the zipper down to the inside of the zipper and sew it into place.
Slip stitch the outside edge of the zipper to the knitting. Again, sew along a straight column of knit stitches so that everything stays in alignment. And, be sure you don't pull the thread too tight. Try to stay relaxed and easy!
That's it! Not so bad, right? And so much more satisfying than dropping it off at the tailor!