French seams are something I get several emails about. For some reason a French seam is something that is intimidating for some sewists. They don't need to be. Like many techniques from sword swallowing to basting, everything is better with practice. If you are not happy with a technique, then try to be more careful each time you try it until you get the results you want. Let me know how that sword swallowing goes.
Here is a French seam in 13 pictures or less. (As always, click on the pictures to enlarge.) To begin with I will demonstrate this on a scrap of batiste found languishing on my sewing machine table and glaring orange thread. The fugly thread is so you can see what I am doing. This is the technique I learned from Lyn Weeks and is demonstrated in her book "Precise and Professional."
This French seam is a flat seam, so I have starched my fabric. (If stitching a French seam using a gathered fabric, I do not starch the fabric that will be gathered.) I have marked the right side of the batiste with a blue marker and will mark my seam allowance using this C-Thru ruler. I buy these rulers almost by the gross. (Okay that is an exaggeration, but I do buy them 3 and 4 at a time. I can never find one when I need it. When I die, my girls are going to wonder if I was dealing C-Thru rulers on the black market.)
I use a 3/8" seam allowance for almost all of my French seams. I find I have more control both in hand and on the machine.
NOTE: If your pattern does not call for a 3/8" seam allowance, alter your pattern before cutting.
I mark both the 3/8" and the 1/4" seam allowances. Make it a habit to mark both seams until you are familiar with your machine. I still mark mine most times. I find it quicker to mark than rip out.
I will stitch the first pass on the 1/4" mark with a zig zag stitch. My machine settings are 2.1width and 0.9 length.
With wrong sides of the fabric together, using a zig zag foot on my machine, I begin stitching making sure that the left hand swing of the zig-zag hits right on that 1/4" mark. Stitch the seam.
This is my first pass. Again this is wrong sides together.
Set your zig zag seam with the iron, or as Lyn calls it, meld your stitches. This helps your stitches sink down into the fabric.
The next step is scary, I trim right up to those zig zag stitches. I use these black Dovo scissors (featured in this post) to do this trimming. They have a serrated blade and have very good control when trying to trim a narrow seam allowance on wispy fabric. If you will carefully cut with a light, steady pressure, it feels like you are cutting perforated paper as your scissors snip into the holes made by the right swing of the zig-zag stitch.
First pass of a French seam, trimmed. Close!
Next press this seam to one side from both the wrong side and the right side.
Now fold your seam, right sides together. This is the folded edge. You want to make sure the edge of that first seam is at the top of your fold. Otherwise you get a pleat in your finished seam allowance. That is not the look you are going for, and it will also take up more fabric into your seam allowance. Resulting in a seam that could be more than 3/8". Do this enough times and you can alter the fit of your finished garment.
I have changed to my edge joining foot and picked up my trusty bamboo skewer. If you enlarge the picture you can see that my skewer is marking a little gulley in my fabric right on that blue 3/8" line and is skimming right along side the left edge of those previous zig-zag stitches. This allows my blade on the edge joining foot to sew right in that little gulley. Thus making a tiny neat seam.
Second pass of the French seam. As you can see the first run of stitches are encased inside the finished seam. Making a strong, neat seam. Press this seam flat as it was sewn to set your stitches.
Open the fabric, press to one side on the wrong side first.
Then press on the right side. Tidy, tiny seam every time and not a fuzzie to be seen!
Don't let a French seam scare you off!