Constructing Cigarette Pants: Flat-Lining

I mentioned last time that I'm flat-lining these pants to finish the inside seams.  Here's how I did it!

After I cut the wool, I left the pattern pieces pinned to the fabric and laid out the whole bundle onto my underlining.  I'm using a very shifty stretch silk, kind of like a lightweight crepe, from Vogue Fabrics (where I work), so the grip of the wool was important in keeping the fabric stable so I could cut straight.  Since the silk doesn't have a visible grain, I measured up from the fold to the grainline on my pattern piece, keeping them parallel from waist to hem.

(This silk photographs really strangely, especially against my light wood table & floors--it's more of a goldenrod color, somewhere between orange and yellow.)

Then I used my tailor's chalk to mark around the outline of the pattern piece.  Instead of cutting the underlining the same size as the outer fabric, however, I added an additional 5/8" seam allowance along the vertical edges.  That extra fabric will be wrapped around the raw edge of the wool inside the seam, finishing it neatly.  You don't need it at the top and bottom, where the raw edges are already finished by the hem and waistband.

To join the two fabrics, I put the pieces together with the edges flush.  You will get a big vertical tuck of loose underlining down the center of the piece--that's what it's supposed to look like.  Sew a 1/4" seam along the vertical edges.  I line up my needle so it's exactly 1/4" away from the edge of my presser foot, then use that as a guide.

Then turn the whole piece inside out.  Don't allow the outer fabric to roll--you want the underlining to wrap around it completely, like a seam finish.

From here, you treat your underlining like the wrong side of the outer fabric: mark your dart points and any construction lines directly onto it, and sew darts and seams with both layers of fabric acting as one.  All seams will be sewn with your normal seam allowance (which for me is 1/2"), measuring from the edge of the outer fabric.  Mine is heavy weight enough that I could feel it through the silk as I was feeding the seam into the machine.  Press the seam open, and it looks just like a bound Hong Kong finish.

For this particular project, I had a few issues in the fork area--I forgot to allow any horizontal ease there, even though the crotch seam and inseam run diagonal-to-horizontal, so I had to trim the seam and do some fudging and stretching when I flipped it inside out and blah blah blah it's not as neat as I would like.  The wool is also bulky enough that the seams kind of stick out at me in the inseam, and I can't get them to press flat.  I'm going to sleep on it and see if I come up with any other options, but worse comes to worst I will rip back a few stages (I've already sewn the crotch- and outseams) and topstitch along each side of the inseams to keep them flat.  You live you learn!

P.S. Thanks to whoever returned "Quilts! Quilts!! Quilts!!!", it was worth the wait.