How to sew flat felled seams on silk fabric (the easy way)

In this sewing tutorial I will show you how to sew a flat felled seam

This term “flat felled seams” sounds to me a little bit too professional but the technique itself is not too complicated and can be widely used in home sewing.

Flat felled seams can be usually found on denim because they are very strong and durable. You can use a flat felled seam when sewing bedding, sportswear and equipment, men’s shirts, special work clothes, jeans, skirts, trousers, clothes that need to be washed very often, etc. 

But flat felled seams can be decorative also.  And they can be used on lightweight silk fabric. 

A distinctive feature of the flat felled seam is that two lines are visible on one side of the seam, and only one line on the other.

I like to use them even on chiffon and organza (together with French seams). Maybe I am the only one but anyway, to me flat felled seams look awesome. 

I used them recently while sewing my silk fitted sheet. So I can assure you that they are really as suitable for delicate silk fabric as they are suitable for denim. If you would like to read that tutorial on how to sew a fitted sheet (from 100% silk fabric) here is the link.

Please note that some measurements in this article are provided in millimeters and centimeters so if you are used to working with the imperial system please use this chat from my guide “All about a tape measure for sewing”  

If you would like to have the chart as a printable you can go to my RESOURCE LIBRARY (free for my subscribers) and download the chart as a PDF (and print it).

Note: Some of the links on this page are affiliate links. This means I will receive a commission if you order a product through one of my links. I only recommend products I believe in and use myself. 

I think I am doing flat felled seams a little bit differently than I found in available tutorials. The result is the same though: seam allowances are fully enclosed, they are really flat and on one side of the item you can see two stitch lines and on the other side only one stitch line.  

So what are the steps to sew flat felled seams on silk (and other lightweight fabric as well)?

Step 1

Pin the fabric right sides together (wrong sides out). 

I need to mention though that for silk fabric you need to use very sharp extra fine glass heads long pins (so they don’t leave any holes in the material)

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Stitch keeping correct seam allowances for your project. For example, if your seam allowances are ⅝ inch then stitch 5/16“ from the edges – divide the seam allowances in half. 

For this tutorial I used scrap pieces of silk fabric – just to show you how to sew a flat felled seam. I didn’t have any particular project in mind. So I stitched 5/8 inch (or about 1.5 cm) from the edges with the stitch length 2.2 mm for silk fabric. By the way, I have a tutorial on setting the stitch length for different fabrics and for different stitches. Check it out if you are interested.

And also I always use 100% silk threads to work with silk fabric. They are smooth, quite strong, yet delicate, have a lustrous sheen, and glide through the silk fabric with amazing ease. Remember that your thread shouldn’t be heavier than the fabric.

Silk threads are just amazing! They are very thin but they are also very strong. 

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Step 2

Press seams first and after that fold the seams exactly along the stitch line and press again.

Step 3

Increase stitch length to 2.7 mm and stitch over folded seams 3/16 inch (or 5 mm) from the first stitch line ( or from the folded edge, which is the same in this case).

Step 4

Trim excess fabric carefully (so you don’t cut stitches) close to the second stitch line using small scissors. Thoroughly press this turned-under seam on one side (the one you just trimmed) flat.

I recommend Duck Bill Scissors, I can’t live without these magical scissors anymore. They have a wide outer edge that lifts fabric (that was cut) away without harming the threads. The handles are curved and because of this, your hand won’t be in the way while you trim the fabric. And these scissors are really sharp.

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Step 5

This is the final step – carefully stitch the seam along the folded edge keeping even distance from the other stitch line and not going off the folded edge. Try to sew as straight as possible for a professionally looking finish. I have a very popular tutorial How to sew straight, check it out. 

Here it is, the flat felled seam. Durable, reliable and beautiful.

I think this method makes a great finish if you can sew it accurately and is faster and easier than the one I found online. I am pretty happy with the result. 

Did you find this tutorial helpful? If so, save this pin (see below) on your sewing board so you can come to this tutorial later when you are ready to sew flat felled seams and follow me on Pinterest for more tips, tutorials, and inspiration! 

Ready to take the next step in your sewing journey?

Check out more step-by-step tutorials from my blog

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  1. Margaret

    My compliments. Recently retired, time to return to sewing. Lucky now have 7 grandkids for sew for! Never saw this sewing with bobbin thread before! Must try. Thanks

    • Olga Balasa

      Thank you! I know many retired women going back to sewing. There are many reasons why we start sewing again. Yes, you are lucky to have so many grandkids to sew for! There are so many patterns and fabrics to choose from!

  2. Threads

    This is a great tutorial! I recently sewed a canvas sunshade for camping that used a similar flat felled technique, I think I will try this on the next project…it looks even easier and lies beautifully. Hmmm, I have some linen and a great tunic pattern, that sounds perfect to try it out… Thanks Olga!

    • Olga Balasa

      Thank you! To me, it was the only way to sew flat felled seams on chiffon, but it will certainly work with any fabric. And a tunic from linen sounds great!


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