Feet · Overcasting

False French seams for fine fabrics

Ah, summer! Hot weather means ice cream, lightweight fabrics and frequent washes. In sewing terms it means that the seams must be strong enough not to unravel in all those washes, which is easier said than done because lightweight fabrics are often loosely woven too, so they fray and disintegrate easily. But we don’t want to leave great big seams in those lightweight fabrics – that’s ugly.

The solution is normally French seams. However, in order to avoid the seam allowance peeking out of the seam on the right side, you have to cut it quite short, so the seam starts unravelling easier than you would like to. And it is fiddly to make.

My first answer was to stitch over the folded seam allowance in order to prevent it from unravelling. But that made it rather stiff and interfered with the flow of the material. Then I remembered hemmed seams and went for a compromise.

  1. Sew two pieces together with straight stitch as usual, right sides inside, with a 1/2 inch (1.3cm) seam allowance.
  2. Cut the seam allowance of one of the pieces to half width.
  3. Set the machine to 3mm wide zig-zag, 3mm stitch length.
  4. Use the felling foot to flip single seam allowance over the double portion and zig-zag it in place.

You now have a seam with three layers of fabric in the seam allowance rather than with four layers as in French seams. But this seam is stitched, so it is not going to unravel quite so easily.

The felling foot is similar to the narrow hem foot, but it flips the fabric only once and not twice, and is much easier to use. It also works on curved seams.

This seam is much stronger and more durable than an overlocked seam, even when you overlock with two needles. Folded fabric absolutely stops fraying.

One thing to look out for though is to make sure that your zig-zag is not too dense – set the stitch length longer if it is. Dense zig-zag will stretch out the fabric and make the seam stiff and “wavy”.

For finer fabric like chiffon you want a slightly different variant of this seam that makes particularly nice looking seams with very narrow seam allowances. It is also made with the felling foot, see this older post.


I wrote the post, published it and then it occurred to me that there are a few points I should add about the felling foot.

Not all felling feet are born equal, and not all “standard” feet will fit your machine. Or rather: they will look as if they fit, but your seam won’t be as neat as mine. And this has nothing to do with skill but with the way the foot fits the machine.

First of all, you need a felling foot meant for zig-zag, with an elongated needle hole. Many fellers are meant for straight stitch only and have a round needle hole! This obviously won’t work.

Felling feet have a groove on the underside that corresponds to the width of the flipped material. These feet come in different widths for different purposes. You need a 3mm or 4mm wide feller for these seams. Set your zig-zag slightly narrower than the feller.

The most important thing in getting a good seam is the alignment of the foot and the needle. Machines are notorious for having slightly different alignments, I am sure this is meant to encourage you (or to force you) to buy optional extras from the manufacturer for stupid money. This is particularly annoying if your machine is vintage and the manufacturer no longer offers suitable attachments for any money.

So you buy whatever felling foot you can find and check the alignment. On straight stitch the needle must be exactly in the middle of the folded part of the seam allowance. Then when you set it to zig-zag, it will do it just right.

If the alignment is a bit off, it can often be corrected by setting the needle left or right rather than centre. Or you could stuff something in the shank of the foot to bring it to the left, or file the shank a bit to bring it to the right.

It is worth while to get it right. The felling foot is a great thing, and you will catch yourself using it again and again in most unexpected places. 😉


4 thoughts on “False French seams for fine fabrics

  1. Thank you for this! Such a brilliant tip for a relatively new sewist. Much appreciated! Now I need to research an appropriate felling foot for my machine.


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