French seams are not just for garments! They elevate any project to the “designer” category and our friends at Sew4Home give you loads of helpful tips.
In general, the purpose of any seam finish is to prevent fray-prone fabrics from raveling beyond the sewn seam and leaving a hole in your sewn project. However, regardless of fabric type, finishing a project’s inside raw edges will not only elevate the final appearance, it will also elevate your sewing skills to a professional level.
If a fabric is sheer and/or delicate, it’s an ideal candidate for a French seam. Heavyweight fabrics can be used but are a challenge because of the bulk in the seam. As with all techniques, it’s always best to test the French seam on scraps to determine if it’s truly the best finish for your fabric type. In general, light to medium weight fabrics are perfect for a French seam finish. One other note of caution, the French seam technique is best used on straight seams.
In terms of tools, you need a needle and thread appropriate for your selected fabric type, a standard presser foot, sharp scissors, and an iron and ironing board – pressing is a big part of the French Seam technique.
Understanding the seam allowance measurements
The French seam can seem confusing at first because it’s a two-step seaming process: first you sew with wrong sides together, then with right sides together. Anyone who is an avid sewer will immediately feel they’re doing something gravely wrong by placing the fabric wrong sides together. But, fear not!
Since the French seam technique is based in garment sewing, our sample steps use a traditional ⅝” garment sewing seam allowance. In step one, you sew a ⅜” seam wrong sides together. The seam allowance is trimmed to ⅛” from the line of stitching, which means you are trimming away ¼”. In step two, the fabric is placed right sides together along the previously sewn seam, and sewn with a ¼” seam allowance, enclosing the raw edges of the first seam. Confused yet? The important part to understand is how the total seam allowance of ⅝” is maintained, ⅜” + ¼” = ⅝”.
If you’re working on a home décor project, using a standard ½” seam allowance, it’s best to add ¼” to all the fabric cuts where you’ll be applying the French seam technique. This allows you ¾” with which to work. Why? You need that little extra to complete the process, otherwise you’d be working with very tiny seam allowances. You will sew at ¼” and then at ½” – but because you added in ¼”, you use up that first and then your final seam is ½” to match with the rest of your construction.
The traditional French seam
As mentioned above, we are using a standard garment seam allowance of ⅝”. We are also using a contrasting thread so you can see the stitching clearly on the fabric. You would use a thread color to match your fabric.
Set up your sewing machine for a straight stitch, with the appropriate needle and thread for your fabric type.
Place your fabric wrong sides together. Pin as needed.
Stitch a ⅜” seam along the raw edge.
It’s just a plain seam. See… nothing to be afraid of even though your fabric is wrong sides together.
Trim back the seam allowance to ⅛”, trimming away to ¼”. Why stitch then trim? So the fabric fibers do not poke through the final seam.
Press the seam allowance together and to one side. This is an important step so don’t skip it! Pressing the seam helps maintain an accurate seam allowance and will make it easier to sew along the seamed edge in the following steps.
Now, fold the fabric right sides together. Your sewn seam becomes the new edge of the fabric.
Press again along the seamed edge. Lightly pin in place if needed.
Sew ¼” from the seamed edge, enclosing the raw edge of the first seam as you sew.
NOTE: If you have a Quarter Inch Seam foot for your machine, it will help you keep an accurate seam line.
Press this second seam to one side, and admire your professional French seam finish from inside and out!
For more helpful information on machine sewn seam finishes check out Sew4Home’s four-part tutorial on the subject:
By: Liz Johnson, Senior Editor, Sew4Home – a Janome Exclusive Studio