Voulez-vous coudre avec moi?: How (and why) to sew French seams

Hey there, my fabulous friends! Perhaps you’ve noticed that it’s been eerily quiet around here, and that’s because I’ve been on the other side of the world taking some much-needed time off with family and friends. I’d originally planned to cram in a bunch of blogging and photography and admin work while I was away from the sewing studio (the machine tends to funnel my attention away from all other tasks when I’m within 20m of it), but in the end I barely cracked the laptop and I have zero regrets. My mind needed some time to chill out just as much as my body did.

Leading up to the trip, I pushed out a lot of sewing projects that I didn’t share many glimpses of (partly because some are part of a not-Palm line of side-hustle, partly because some are still Top Secret, partly because I barely had time to stretch my wrists, let alone write a decent IG caption), many of which just happened to feature French seams. I thought this was a great opportunity to discuss not only how to sew this seam finish, but why it’s a great technique to keep in your costuming toolkit.

Pssst… to help offset the costs of running the site and developing new patterns, I may include affiliate links from time to time (including in this post), which means that if you click the link and purchase a product I’ve mentioned, I will receive a small commission from the sale. I promise that I’ll only include affiliate links that are relevant and contextual, for things that I would have written about anyway, and I’ll always indicate which links are part of an affiliate program. For more information, please see my Advertising and Disclosure Policy.

Pardon my French, but what le heck is a French seam, and why would you do it?

Close-up of French seams, inside and outside the garment

A French seam, despite the name, requires no translator. It’s simply a method of sewing a seam so that the raw, cut edges of the fabric are fully enclosed within two lines of stitching, leaving a neat, narrow seam allowance that is pressed to one side. You don’t need a serger, extra lining fabric or bias binding, or any special equipment. Just time and patience! In a nutshell, you sew one pass with wrong sides together at half(-ish) the full seam allowance; then you trim close to the stitching, flip it right sides together (the usual orientation for most seams) and sew a second pass that captures the raw edges in the channel between the two lines of stitches. This makes it a great choice for finishing:

  • woven fabrics that tend to fray, because the edges that would normally fray are protected inside their little seam sandwich, hiding away hairy edges and preventing friction that would make fraying worse;
  • delicate fabrics that could benefit from two lines of stitching as a defence against wear-and-tear;
  • sheer or translucent fabrics where the “guts” of your sewing will be on display;
  • unlined garments where the insides might show and you want it to look as clean as the outside, such as:
    • skirts or dresses with long slits;
    • capes, coats, and cloaks;
    • really full, twirly skirts;
    • a garment you plan to remove.

…as in, lots of stuff we routinely put on stage, especially in burlesque, bellydance, and lots of other dance arts.

Now, even if your garment meets all of the above criteria, French seams may not be the only or best option. Several other techniques exist that could also enclose your raw edges and look hawt on the inside (eg. Hong Kong finish, felled seams, full or partial lining, etc.) that each have their own pros and cons. French seams tend to work well when you have a long(ish), not-too-curvy seam to deal with, and you want the outside to look like a totally-normal-nothing-to-see-here seam with no topstitching. It might not be ideal if:

  • you’re sewing with knits rather than wovens – because the yarns interlock differently, knits don’t tend to fray like woven fabrics (though some will ravel or get ladders), plus stretch knits might be prone to bubbly or wavy seams using this construction;
  • your seams are very curved – the original width of the seam allowance, and the flipping, and the two passes of stitching may make it more difficult to sew tight curves accurately and cleanly, plus pressing curves is a dilemma if you can’t clip or notch without compromising your stitching;
  • you expect that the garment may need to be altered for fit in the future – unlike some seam finishes that are pressed open, you can’t leave extra seam allowance as insurance to let out the garment in the future, and even what moderate seam allowance you started with is partly trimmed away during construction of the seam, making it tough to retro-fit changes once it’s all together;
  • you need minimal bulk at the seams – you’ll end up with almost four layers of seam allowance all pressed in the same direction, which could be a downside in very tight-fitting garments or with bulkier fabrics;
  • you aren’t confident stitching small (1/4″ or 6mm) seam allowances accurately.

Also note that just because you choose to use French seams in one part of a garment, that doesn’t mean you have to commit to using them for everyseam. You can totally evaluate this on a seam-by-seam basis.

OK, I’m sold, but how do I do it, s’il vous plaît?

(First: an apology. I had loads of pictured prepared to help you visualize each step below, but WordPress changed some interface features while I was off romping with the kangaroos, and, (amongst other things, like losing seamless Markdown integration, cue endless swearing) after three (THREE!) days of trying fruitlessly to get images to show up in the correct place at the correct size, I must resign myself to one measly photo or risk never posting anything at all. I hope to update this post Soon™ with the missing images, or at least a supplemental video. In the meantime I hope you can make sense of my jet-lagged prose.)

Step 1

Check whether your pattern calls for either 1/2″ (12mm) or 5/8″ (15mm) seam allowances in the area where you’re planning to use French seams. If it calls for a smaller seam allowance, like 3/8″ or 1/4″, that might be a sign that this area is not a good candidate for this construction method; however, if you’re sure you want to forge ahead, you’ll need to re-draw the seam allowance so it equals a total of 1/2″ (12mm) (or 5/8″ if you prefer).

Step 2

Place your pieces wrong sides together. You eventually want your second pass of stitching to be sewn at 1/4″ (6mm) from the first, so subtract 1/4″ (6mm from your starting seam allowance), ie.:

  • if you are starting with 1/2″ (12mm) seam allowances, stitch your first pass 1/4″ (6mm) from the cut edge);
  • if you are starting with 5/8″ (15mm) seam allowances, stitch your first pass 3/8″ (9mm) from the cut edge.

Step 3

Trim the raw edge to about 1/8″ (3mm) from your first line of stitching, making sure to cut away any fluffy frays. This ensures none of the raw edge will get caught in the final seam that would show on the outside of the garment. Be careful not to clip through any of your stitches, and try to avoid trimming too close to them.

Step 4

Flip and press this teensy seam so that the raw edge is sandwiched between the pieces, which are now right sides together as usual. Depending on your fabric, you may find it helpful to press the seam flat to one side first, before flipping it and pressing that crisp edge.

TIP: use a silk organza press cloth ($) over your delicate fabrics to prevent scorching or melting; silk is a natural fibre, so it won’t melt, either, and organza is sheer, so you can still see what you’re doing! 

Step 5

With right sides together, sew your second line of stitching 1/4" (6mm) from the pressed, folded edge. Press this seam to one side.

That’s it!

You’re done! Admire your beautiful garment guts, ready for their stage début!

How to print and assemble your PDF pattern

Hello, my sparkling storytellers! If you’re new to digital sewing patterns and templates, getting all the pages to fit together can feel a bit overwhelming at first. But don’t worry, because in this quick tutorial, I’m going to show you all the tricks to get your Palm Patterns PDF pages pieced together and ready to sew. You can read along below, or watch this helpful video for the full audio-visual extravaganza:

Downloading your pattern

The first step, of course, is to get yourself a pattern – when you purchase a pattern from my Etsy shop [THANK YOU], you should see a link to View Your Files immediately after completing your checkout steps. This will take you to the Downloads section of your Etsy account. Keep in mind that you can’t download your files via the Etsy app; you will need to sign in through a regular browser, and if possible I recommend downloading at a computer rather than onto a tablet or mobile device. You’ll also receive a link to download your files in your confirmation email, and you can always find your digital purchases later in the Purchases and Reviews section of your account.

Printing your pattern pages from your home or office

One of the most important steps to a successful project is making sure that your pattern prints out at the right size! For the most reliable results, I recommend opening your PDF files in either Preview (on a Mac) or Adobe Reader (on other operating systems). When you’re ready to print, pay careful attention to the printer settings box that pops up on your screen. You should see options to scale or resize the document, and most printer settings will try to shrink or expand the document by default, to make the most efficient use of the page. YOU DO NOT WANT THIS. DO NOT LET THE PRINTER BOSS YOU AROUND. You’ll want to find and check the box that says something like:

  • SCALE: 100%

…and so on.

If the printer shrinks or enlarges the pattern, you may end up with pieces that don’t fit together correctly and won’t fit your body as expected, which would be very disappointing.

You can print on either LETTER SIZE or A4 SIZE paper. The file is designed to fit comfortably on both types of paper, and the only difference should be how much margin you end up trimming away.

Each Palm pattern has a test square on the first one pattern tile – it’s a good idea to print this page first, measure the test square to confirm the scale is correct, and then print the rest of your pages.

UPDATE: Light or fine lines and sybmols may not print clearly at lower print quality settings. For best results, choose normal or high print quality, and avoid “economy”, “draft”, or other ink-saving settings.

Printing from a copy shop, public printer, or email-to-print services

If you don’t have a printer at home, don’t let that discourage you! I often print my patterns at print shops and my local library. You’ll want to be very cautious about printing methods that don’t give you much insight into the final print settings – I’ve had mixed results with my library’s email-to-print service and with printing directly from a USB drive at a touch-screen kiosk. If you’re working with a new system, it’s an especially good idea to print your test page before committing to a dozen pages that might come out at the wrong scale.

Assembling your pattern tiles

Phew, OK, we’ve got our pattern printed and we measured the test square and everything is groovy! Now it’s time to put the pieces together.

Some patterns will have pieces that fit entirely on one page, but most will have pages that need to be trimmed, aligned, and fit together. It’s a bit like doing a really simple puzzle. All Palm Patterns are designed to be assembled by trimming the bottom and right margins along the dotted grey lines. You can use scissors to trim, or a ruler and a knife, or a guillotine if you’re fancy. Regardless of what kind of blade is doing the work, you want to cut as precisely on the dotted line as you can manage.

After you’ve trimmed the margins, take a peek at the bottom left corner of each page. The pages are labeled a bit like a map or a spreadsheet, with both a letter and a number, eg. A1, B3, etc. The letters are the rows, running across grid. The numbers are columns, running up and down the grid.

Line up each pattern tile with its neighbour, and carefully tape the trimmed edge to the dotted line on the other page. Check that your pattern markings are lining up nicely and your pages are laying flat and smooth. The more precise you are at this stage, the more accurate your pattern will be!

When your whole grid is assembled, you can trace or cut out your size and start sewing!