Have you ever had the lining or facing of your garment keep rolling and peeking out from the inside? There is a solution for that, and it’s called understitching. Understitching is a technique that is often used on necklines, armholes, and the top edge of a lined skirt. And it’s done by stitching the seam allowance to the lining/facing, very close to the seam. If done correctly, the stitching is unseen from the outside, and your lining will stay hidden and in place on the inside!
Let’s take a look at how to use this simple technique…

For this sample, the print is the main fabric, and the solid colour is the facing/lining.

With right sides facing each other, stitch your pieces together.
NOTE: if you are working with a curved seam, like a neckline or an armhole, now is the time to clip or notch your seam allowance.

With the wrong side facing you, open up your seam and press the seam allowance towards the facing/lining. Press it from the right side as well to make sure its good and flat. Pin to keep in place if necessary.

Stitching on the facing/lining and through the seam allowance, sew a line as close as possible to the seam line, about 1/8 – 1/4” away. I used the inner side of my presser foot as a guide.

This is what it should look like from the right side (L) and wrong side (R).

Now press your facing/lining to the inside. You’ll see that it rolls nicely to the backside, so that facing/lining won’t peek out from the front.