Steps To Sew The French Seam And The Flat Felled Seam

When it comes to sewing seams that are both strong, clean and beautiful, French seams and flat felled seams are two top contenders. But what’s the big difference? A French seam, my personal favorite, hides the raw edges of the fabric on the inside, making it perfect for lightweight or sheer fabrics. French seams can be used on some heavier fabrics as well but you’ll need to be very good with sewing and cutting the fabric so maybe wait until you’ve got sewing down and your confident of your skills. On the other hand, a flat felled seam is stitched down, leaving no raw edges out in the open, ideal for heavy-duty clothing like jeans or jackets but can be used on lightweight fabrics as well.

These techniques aren’t just trends—they have some history. French seams date back to when dainty, elegant garments required neat finishes, while flat felled seams became the go-to for durable, industrial clothing. Both methods have stood the test of time, proving their worth in both home sewing and professional ateliers.

So, why bother with these seam techniques? Well, they add durability and give your clothes a clean, polished look. French seams are all about that delicate, almost invisible finish, whereas flat felled seams scream rugged durability. And hey, who doesn’t want their projects to look the part while lasting longer?

Before jumping in, having the right tools is crucial. A sharp pair of fabric scissors, a trusty sewing machine, and the right thread should be on your checklist. Also, a good iron and ironing board are your best friends for pressing those seams perfectly.

For my new sewers out there, don’t sweat it if your first few tries aren’t perfect. Mastering these techniques takes patience. Start with scraps and practice, practice, practice. Keep a seam ripper handy—it helps fix those inevitable mess-ups while learning but be careful with the seam ripper as it can tear the cloth at the seam and then the garment most often is ruined but they do come in handy so learn how to use them with care. Things might get a little tangled at the start, but with patience and persistence, you’ll get there.

Mastering the French Seam: A Step-by-Step Guide

Getting comfortable with French seams starts with picking the right fabric. This technique really shines with lighter materials—think chiffon or voile, cottons, but can also be used on silks brocades and many fabrics but practice with inexpensive cloth.  Remember bulkier fabrics just make it all tough and tricky when learning. Grab some lightweight cotton for your practice runs, as it’s forgiving and easy to maneuver.

I. For the first step, consider how big your seam allowance is for your garment.  When using commercial patterns the seam allowance is 5/8’s of an inch, which is what I will typically use throughout my website because most students learning clothing construction will use commercial patterns. The French seam is comprised of two rows of stitching, and you can calculate however large or small the two rows of stitching will be. Most commonly the first row of stitching is a 3/8″ and the second row can be at 1/4″. We know that 3/8″ and 1/4″ equals 5/8″ therefore making the seam allowance finish at 5/8″. So keep in mind whatever size your seam allowance is your two rows of stitching needs to equal your seam allowance measurement.

2. If we are using the 5/8″ seam allowance you’ll stat by pinning the wrong sides of the fabric together. Yes, that sounds counterintuitive for students accustomed to the usual right-side-together rule. This creates a visible seam initially, but remember, it’s part of the magic. Now you’ll sew the seam together with a 3/8″ seam allowance (For French seams I usually pin perpendicular to the seam so I can sew over the pins). Next take out the pins and trim the seam allowance to approximately 1/8″. You want your seam allowance small here; as it will be enclosed later in the second row of stitching, leaving only a narrow allowance on the inside.  Then you’ll need to press the seam.  You won’t be able to press the seam open as it’s too small so just press it to one side as neat as possible.  Right now this small seam is on the good side of your fabric and the next seam will bring the seam finished and to the inside.

3. The next step is to pin a 1/4″ seam from the wrong side burying the small 1/8″ seam allowance inside the second seam to be sewn.  Now go ahead and sew the second seam at 1/4″ and your done with the sewing, you’ll just need to press the 1/4″ seam allowance nice and neat and the magic happens-now the small 1/4″ neat seam is on the inside and it’s clean small and simple.

4. Lastly, assess your handiwork. Look over your seam to ensure it’s strong and even. Give it one last press. Check for any raw edges escaping and enjoy the satisfaction of a job well done. With every project, these skills sharpen, and before you know it, you’re a French seam pro!

Perfecting the Flat Felled Seam: Techniques and Tricks

Flat felled seams are the go-to for that sturdy, polished finish, often seen in denim wear. Fun fact, at one time jeans were workers pants and to make strong sturdy seams the flat felled seam was perfect to use. To start off right, fabric choice matters here. Fabrics that are too heavy might be challenging to work with, so medium-weight cottons are ideal at first.

1. For the initial stitch, basically this will begin like sewing a regular 5/8″ seam or whatever size seam you use (however if your using time 3/8″ or smaller seams the flat felled will be no good for you). You’ll begin with your fabric good sides together making sure to align those edges neatly together before sewing, because your first stitch line determines how precise the final look will be. Again this seam like the French seam incorporates two rows of stitches and consistency is key with this seam—use a guide if needed to maintain an straight and even distance from the edge when you sew this first seam.

2. As in all seams, if you sew a seam you need to press the seam.  Press this seam open as usual.

3. Now for trimming. With your first seam sewn and pressed you’ll trim one side of the seam allowance a little bit more than 1/2. This step reduces bulk and allows the seam to lie flat and fold easily. A pair of sharp scissors makes all the difference here, keeping cuts clean and smooth.

4. Let’s sew the second seam which involves folding the wider seam allowance over the trimmed edge side so that it is as straight as possible, use a guide if necessary. Try to make the fold (based on 5/8″ seam allowance) about 1/2″-3/8″ and stitching it down as close to the folded edge as possible. Pin perpendicular and sew it as straight as possible. This seam isn’t hard it’s just tricky trying to make it even and straight, so practice this seam a few times before using it on your good project. When done well this seam encases the raw edge completely, giving it that nice, clean finish you’re aiming for. Using a straight stitch, sew steadily to secure everything in place. It pays to take it slow to get those stitches just right.

Lastly, let’s talk about creative adaptations. Flat felled seams aren’t just for jeans or other pants seams. They can be a beautiful addition to side seams on shirts or even bags, giving any project a clean look. Adjust the technique slightly depending on fabric behavior, and practice makes all the difference. With time, you’ll tailor this technique to any project, making your pieces uniquely yours.