a flat fell seam is a type of stitch that joins materials together. you would use a flat fell seam for something like denim because it is the strongest type of stitch.
Jeans are constructed with several seaming techniques but the seam you are probably inquiring about is the "flat-fell" seam. Sewmetheway
There are 11 types of seams which include: abutted, enclosed, exposed, false french, flat-felled, french, fused, glued, hairline, lapped seam with raw edges, and finally overedged seam.
Ah, a flat-felled seam is like a little hug for your fabric pieces. It's when you fold one edge over the other and stitch them together, creating a smooth and sturdy finish. It's a lovely technique that adds both strength and beauty to your sewing projects. Just remember to take your time and enjoy the process!
Three self-neatened seams include the French seam, the flat-felled seam, and the bias-bound seam. A French seam encloses the raw edges within a folded seam, providing a clean finish ideal for lightweight fabrics. The flat-felled seam features one seam allowance folded over the other and stitched down, creating a strong, durable seam commonly used in denim. The bias-bound seam encases the raw edges in bias tape, offering a neat finish while allowing for flexibility in fabric types.
After the seam is sewn, a seam finish can be applied to the outside edges of the seam allowances to keep them looking neat and prevent fraying. Examples of seam finishes are a zig-zag stitch, using pinking shears for a pinked finish, french seams, flat-felled seams, etc.
flat seam is used for decorative purpose. Seam edges do not overlap but flatted together. Seam is constructed with a minimum of 3 fabrics.
The three types of seam are Plain seam, French seam and Ancient or Old German flat seam.
sew a seam with a 5/8 seam allowance. then on ONE SIDE of the allowance, trim it to half the size. don't measure just eyeball it. then press the seam allowance to one side with the [now] short allowance on top. fold the longer allowance over the shorter and press it. then flip the whole thing to the other side of the seam and press again. finally, topstitch as close to the edge as you can. flat felled seams are the strongest and are used where ever a great amount of tension exists, such as the seams on your jeans, or the shoulders in a shirt/jacket. they are also used in sports clothes.
An open seam is a general purpose seam. An open seam is two pieces of fabric sewn together, and then the seam allowances are pressed open, creating a flat and clean seam line on the right side of the fabric.
flat felt seam
.... This question is open to interpretation. Knits and spandex sportwear/swimwear is finished on a serger or overlock machine. Two neat stitch lines appear on the 'right' side of the garment. When you reverse the fabric you see that these stitch lines are connected (overlocked). Double stitched may refer to two rows of stitching you typically see on Denim jeans. This is a flat felled seam- no loose ends or seams to overcast to prevent the denim from unravelling. A double stitched seam may be straight stitching on a seam and then stitching another row alongside it.
If you are working with a standard pattern for leisure wear summer shorts, a simple straight stitch seam will be good enough. If you are making sports shorts, that will require a stronger finish, I suggest a flat fell seam.