A flat fell seam is the seam you often find on the inside leg seam of a pair of jeans. It has two rows of visible stitching on the outside and on the inside all the raw edges are encased, making it a neat and super strong seam. It is one of those style details that has become synonymous with denim. The iconic double row of orange toned stitching is often found on ready made denim jeans and jackets.
You can add a flat fell seam to your own handmade jeans, jackets or any other style you like. I have made a hot pink denim Mary dress to show the stages for this tutorial. I used matching standard thread. You could also make more of a statement by using contrast colour threads, decorative or topstitch threads.
You might like to sew some of the seams like this but not all of them, it works best on straight seams, you could turn corners but it would be pretty tricky. It is also worth taking into consideration the seam allowance and type of fabric you are using. Seam allowances less than 1.5cm will be very fiddly and tricky to achieve nice flat fell seam results. Likewise if your fabric frays a lot or has a soft floaty handle you may find this quite difficult.
For this dress I stitched flat fell seams down the centre back and both side seams.
- The flat fell seam begins with wrong sides together. Stitch the full seam allowance together with wrong sides matched.
2. Trim one side of the seam allowance down to approximately half the width. The more accurate you can be with your trimming the better, it will help with the next steps.
3. Press the larger seam allowance over the trimmed seam allowance so that you have a nice flat seam.
4. We now need to turn the raw edge of the wider side seam. This little trick can be helpful if your trimming in step 2 was pretty accurate. Fold the panel so that the seam is on the edge. You can then turn the raw edge in using the edge of the small raw edge as a guide. Press as you go.
5. Open the work back out and press again to keep the seam as flat as possible. Pin the folded edge down.
6. Stitch close to the folded edge approximately 1-2mm away from the folded edge.
This is the reverse side of the seam. All raw edges neatly hidden away!