When I first picked up sewing again as an adult, I visited my mother who showed me how to use the machine I had inherited from my grandmother. It was at this visit she first introduced me to French seams, a technique where the item is sewn with wrong sides together, then turned and sewn with right sides together. This is a really neat technique for woven items to enclose an exposed seam, or keep a high-wear seam from fraying.
When I made my final version of the new DIBY Club pattern, The Duchess skirt, I knew I wanted to be sure the seam at the back looked nice since it can be visible from the front.
French seams aren’t traditionally used for knit fabrics because there isn’t much of a need – exposed, serged edges look quite professional, and can even be a design feature in some garments. Plus knits won’t fray anyway.
But maybe you’re working with an item for someone with sensory problems who doesn’t like seams, or you just want a really clean look on something visible in a finished item.
So here is a step-by-step guide to help you achieve a really nice French seam on your knit garments!
Step 1: Put your fabric wrong sides together, and sew with a minimal seam allowance on the right side of the fabric.
Because the Duchess has a 1/2″ total seam allowance, and I am using a serger for this step, I serge right along the very edge of the fabric.
Don’t worry though, you can scroll down for tips if you’re using a pattern with a smaller seam allowance!
If you aren’t using a serger, I recommend a 3/16″ to 1/4″ seam allowance for this first seam. You will want to use a good stretch stitch, such as a triple stretch stitch, lightning bolt, or zig-zag. Once you’ve completed this step, you may opt to trim this seam allowance closer to your stitching to make the next step easier.
Step 2: Fold your newly sewn item with right sides together, wrong side out.
This is where we will deviate from a traditional French seam – ideally, you would fold this at the seam and then press it for a nice, crisp edge. I encourage you to do this if you’re using a fabric that will hold a press, but for this particular skirt I used a wonderfully drapey ITY. Amazing skirt material, but it isn’t going to hold the press I want! Going slowly down the length of the seam, I press with my fingers and then – and this is important – clip or pin the FLIP out of it.
You want to be sure you’re sending it through your machine as close to “crisply pressed” as possible. When finished, I had a clip approximately every 2 inches.
Step 3: Sew down this fold, just off the edge of your original seam allowance, to enclose your raw edge or serger stitching. I feel this looks best if you are using a “straight” stretch stitch, such as a triple stretch stitch or a lightning bolt.
You can see here I opted to use a lightning bolt, as narrow as possible with a moderate length of 3.5 out of 5. Go slowly to be sure you’re stitching off the edge of the seam.
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Tip: Use your thread tails from the first seam to hold the edge at the end, and to be sure the fabric isn’t stretching or pulling too far inward.
And now you’re finished! On the outside it should look like a regular seam, but on the inside of the item it’s fully enclosed and looks very neat and clean!
From here you can easily finish the garment however you like!
Smaller seam allowances: Many PDF patterns utilize a half inch allowance, but some only use three-eights or one-quarter inch. When I use four threads on my serger, my finished seam comes out to a quarter inch, so some adjustments have to be made. You have a few options for this:
- Use your regular sewing machine, taking a smaller seam allowance for your first pass
- Remove the left needle and use a narrow 3-thread serged seam
- Trace your pattern and draft a wider seam allowance before you cut your fabric
Exposed edges after sewing your second seam: If you accidentally sew too close to your seam allowance, you might end up with some exposed raw edge or some serger stitching along the outside of your finished item. Obviously this ruins the aesthetic we’re going for with the French seam, but don’t despair! This is a very easy fix. You may opt to seam rip and re-sew, but because the problem is that you’ve sewn too close to the edge you can simply re-sew this area, going slightly further in from the edge.
A bulky seam: Serging in the first step can definitely make for a bulkier seam overall, so if you’re looking to keep it as small and flat as possible, use a sewing machine for the whole thing.
Hemming: A French seam can make your final hem bulky, but your final stitch down the item is your only visible seam in the hem. You can safely trim the bulk of the final seam allowance near the edge of your item, to eliminate sewing through 8+ layers of fabric and ending up with a weird ball on your hem 😉
Can you see yourself using this in a technique? Go ahead and try it on the new, free Duchess skirt from the DIBY Club and share how it worked for you!
Can’t try it now? Pin this for later!