You may know the flat felled seam by another name: the flat-fell seam or a felled seam.
What is a flat felled seam?
With double stitching, this seam is very durable. This is one of the sturdiest seams available. You will find it on jeans, workwear, outerwear or other places where you don’t want any visible seam allowance on either the inside or outside of the garment. Two rows of stitching show on the outside of the garment and a seam line and one row of stitching show on the inside of the garment.
What is a mock flat felled seam?
The mock version looks almost the same on the outside of the garment, but you do see both seam allowances on the inside.
To make the mock version, start by edge finishing your fabrics. Here I used my serger, but you could use an overcast stitch on your machine or zig zag. I wouldn’t use any of the edge finishes that add bulk to your seams.
Place your two fabrics together RIGHT sides together and sew your seam line. Press both fabrics to one side. This will be the side that you stitch to finish this seam.
Here is what the inside of this seam looks like. You can see I pressed the seams to the left.
Using your topstitch foot, move your needle two positions into the seam allowance and stitch. Then, switch your machine foot to the basic foot and sew 3/8-inch from the fold of the seam line. This will match the flat felled seam.
Here is the finished mock version on the right side of the garment:
I used both of the seam finishes on this dress. Here is the side seam with the true flat felled seam finish. I matched the double stitching to sew on the pockets and used the raw edge of the denim to finish off the top of the pocket.
Here is the bodice seam with the mock version:
And, just in case you are curious, here is the finished dress. Super comfy and I can layer sweaters when the temperatures are cooler.
What is the difference between a French seam finish and a Flat Felled seam finish?
The French seam is sewn wrong sides together too, but using a small seam allowance. Then another wider seam is sewn on the inside of the garment enclosing the small seam allowance. Generally, the French seam is used for delicate or sheer fabrics.
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