How to do a French seam

French seams are a way to have a garment that’s lovely inside and out. The basic idea is to encase the raw edge of the seam allowance. It’s not hard, and it adds a really nice touch. It’s especially nice on a sheer fabric where you can see the seam from the outside.
I initially used a piece of silk for this demo, but after viewing the photos, I realized it was a bit hard to see what I’m talking about. So I redid the tutorial with a piece of sheer fabric I dug out of my stash. I have placed the photos side by side.


(Click fabrics for direct links for purchase at Warehouse Fabrics Inc.)

Antique Gold

The process

Please click photos for bigger images if you need to see better.

Unlike most things you sew, for this you will place the pieces WRONG sides together. Neither of my fabrics had a right or wrong side, but I labeled for the sake of this tutorial.
If you’re doing a 5/8 inch seam allowance, sew your initial seam at 3/8 of an inch. As I said above, your RIGHT sides are showing right now.
Trim your seam allowance to 1/8 of an inch.
So the view from the WRONG side is the nice side of the seam. I swear my “W’s” were the same size before. Huh.
Now fold your fabric so the wrong side is out and the right sides are together. Your nice seam will be on the visible edge, and the raw edge of the seam is sandwiched inside.
With the RIGHT sides together, sew another seam 1/4 inch from the edge.
Now your raw edge that’s on the inside of the fold is encased between two seams.
Opened up and pressed, here is what it looks like from the wrong side. Basically, the seam allowance pops out, but there is no raw edge. It’s like a nice fold.
From the right side, it looks like a normal seam. See how if it’s a sheer fabric, it’s got a nice, finished look to it? If I were making a garment, I might have made this seam a bit more narrow. You’d have to figure out how to do that based on your alloted seam allowance. Basically, in this example we are using a 5/8″ seam allowance. So initially we sewed 3/8″ and then trimmed and sewed another 1/4″ (2/8″), so that totalled 5/8″.
Just for kicks, I am showing you how a sheer fabric would look with a normal seam that’s pressed open. It’s not that it looks sloppy from a distance, but it’s definitely not as finished looking. And the edges would fray with washing and time. That won’t happen with the French seam.