I, cbott: Trash Bags, Step 2

Step Two: The Liner (and Shell)

Pin the plastic to the lining fabric, making sure the lining fabric is right- (pretty-) side-up. (Don't skip this step--skipping is not worth the time wasted and frustration built.) I found it easiest to pin one short side, then weigh it down and smooth everything down as I pinned the top and bottom edges on my way to the opposite side and the final pinning.

Pin 1/8" from the fabric edges, so the punctures will be hidden in the seam allowance.

Once pinned, fold in half along the long edge and pin the 14" sides together. Sew a 1/4" seam. (I use a stitch length just slightly longer than I use in piecing quilts.)

^---Fold Stitch----^

Despite everything, sometimes shift happens. It's not going to be a problem in the long run. Trim off overhanging plastic from this seam.

Mark the center (the fold line), top and bottom.

If you use pins for this, be sure to first pull the plastic slightly away from the fabric so no holes are poked into the plastic.

Finger-press seam to one side.

Refold so the seam is in the middle (aligned with the center markers).

If shift did indeed happen, assign the wonky end as the TOP of the bag. Pin the best-aligned edge.

Good alignment--this will be the bottom.

Wonky alignment--this will be the top.

Sew a 1/4" seam.

This next step is fiddly, and best accomplished by putting your hand into the bag and pulling the side seam away from the middle, repositioning it to the side again.

Gently pat/pull/fold/smooth things until the points are centered, usually 5" in from the fold or the side seam. Squeeze out any trapped air.

If you're making a lot of these bags, it's worth your time to make a cardboard template for this next step, a right triangle measuring 3-1/8" along sides A and B.

Finger-press the bottom seam away from the back seam. Position the template in the liner bag corner.

Draw a line along the template hypotenuse. Do this on both corners (red dashed line).

Pinning the corners helps keep things from shifting under the needle. You needn't be as careful with the pin placement, as most of the area between the line and the point will be trimmed away.

Stitch on the drawn lines, then trim the corners 1/4" away from the stitching line.

This completes the lining construction.

The Shell (outer bag):

Repeat all the steps above (without the plastic).

Exceptions/Additional Information:

An iron can be used to press the first seam. Press it the opposite direction as the liner's back seam. To determine this easily, butt the shell bottom edge against the liner seam.

When marking the corners, move the template a tiny bit away from the fabric edge. This creates a slightly larger corner seam to accomodate the liner corner.