Okay I'm slightly behind in my sew-along posts, so you get two today - first we're inserting the zip, and this afternoon I'll show you how to make the (optional) lining.
Try the skirt on to verify the fit, pinching the zip opening closed along the seam lines. When fitting, I find it helps to work the zip opening around to the front, and mark the seam line with a pin on each side.
Basic zip insertion
If you've got a seam allowance less than 5/8" you won't have enough to do a lapped insertion, so you'll need to use the basic insertion technique.
First, machine-baste the seam closed to the points you marked from trying on the skirt. Press the basted seam open.
(oops, my seam allowance went a little wobbly there - I rushed it because it was just a quickie demonstration of the technique; you will of course take more care!)
On the inside, place the closed zip along seam line, centering the teeth over the seam. The zip should start about 3/4″ below the top edge of the skirt, so the top of the zip is clear of the waistline seam. Pin in place.
Hand baste along the zipper tape to secure in place, and turn the skirt right side out.
Your hand basting lines will now form the stitching guide - it might also help to mark off the bottom of the zip with a pin. Starting at the top right, stitch down the right hand side. When you get to the bottom (just beyond the zipper teeth), hand-crank the needle so it is in the down position (piercing the fabric), then raise the presser foot and pivot the fabric around the needle. Stitch across the seamline, then lower the needle and pivot again to face the top of the skirt. Stitch up the left side of the zip. When you remove the basting stitches you'll have a neatly concealed zip:
Lapped zip installation
This is the typical kind of zipper insertion technique seen on original vintage garments (commercial ones anyway - home-sewn ones often use the technique above), and I love the neatly tailored look. Note that you will need a zipper foot: This type of installation is impossible without one, though you can just about get away with using a regular presser foot for the basic insertion above. Special thanks to Casey, on whose tutorial this one is based.
First, mark the seam line from the top of the stitched seam to the top edge of the skirt - with chalk, disappearing ink, or basting stitches (I ruled a line with disappearing ink, then traced it with hand basting stitches to make it easier to see on the patterned fabric).
With the skirt right side out, press under the right seam allowance 1/8" from the line. Press the left side under along the seam line.
Position the zip so the teeth are right up against the right fold line. The zip should start about 3/4″ below the top edge of the skirt, so the top stop of the zip is clear of the waistline seam. Pin and hand (or machine) baste in place.
Using a zipper foot, stitch from top to bottom, close to the fold edge.
Lap the left fold over the zipper to meet - and just slightly overlap - the right seam line mark. Pin and hand or machine baste in place, and mark the bottom of the zip with a pin just beyond the teeth.
Now, again with a zipper foot, stitch down from the waist, following the basting line, until you get to the bottom of the zip. Pivot, and stitch across to the edge of the fold. Remove the basting stitches, and you're done!
Use a needle to pull the threads through to the wrong side for a neat finish.