Tutorial: Underarm Bias Binding


Summer is coming, thank goodness, and that means sleeveless tops–yay! Personally, I have a very picky attitude when it comes to the strappy top: I don’t like the armhole to be too low or too loose. I like good coverage so there is never any lingerie hanging out the side, and so I can feel cool without feeling exposed.

There are, of course, a number of ways to go about achieving that: lining (which doesn’t make sense in the summer, as it defeats the purpose of lightweight fabrics like linen), facings (which I generally abhor, as they are the dickie of the sewing world and when done poorly almost always show), and bias binding (my preference, almost always). So below, a quick tutorial for applying bias tape to an underarm on a sleeveless top; this can be adapted to most patterns, so long as they have a bodice with a strap.

For this example, I’m using a Pretty Jane design (and this fabulous Lecien Japanese import print).  The square-necked bodice is lined and finished, and I’m ready to attach the bodice to the dress front and back, which have been stitched at the side seams.  You’ll notice the underarm curve at the left and right; this is what we’re aiming to finish with the bias binding here.

Single-fold bias tape works perfectly well for this process, but I never use the stuff in the store: it’s so easy to make your own, and I vastly prefer to work with 100% cotton any time I can.  I’ve cut a length of unbleached cotton (the same fabric as my lining) on the bias, and have pressed under one edge 1/4″:

At the machine, I’ve lined up the raw edges of the bias tape along the raw edge of the first underarm, right sides together.  I’ll stitch these together with a 1/4″ seam allowance.  Note that the pressed edge is NOT the edge I’m stitching here–we’ve pressed that under for later.

When the bias tape is attached, you’ll have this:

Press the seam allowance toward the bias tape, as you’ll be encasing the seam allowances when we stitch the bias tape down.  If you need to trim some of your seam allowance to get a nice, smooth finish, now’s the time to do it:

I’ve pinned the pressed bias tape down to illustrate the next step: fold the bias tape back over the seam allowances, so that the original edge you pressed under is now on the wrong side of your dress.  We’re NOT stitching yet, but this is where we’re headed:

BEFORE you stitch down the bias underarm, we’re going to attach the skirt to the bodice.  This way, when we finish that underarm, we can complete a bunch of tasks in a single step.  For this little jumper, we’ll need to gather the front and backs first, leaving the bias tape UNgathered:

Front and back with gathers in:

Now we attach the bodice.  With right sides together, place the bodice front over the gathered front skirt.  At the finished edge of the bodice, tuck the corner inside the bias tape, right up against the seam:

Then fold the bias tape back over it so it’s enclosed:

When both right and left of the front are complete, you’ll have this–do you see how we’re going to get a clean finish and cover that underarm at the same time?

We’ll do the same with the backs.  At the underarm, tuck the edge of the bodice inside the bias tape; at the back opening, fold the skirt fabric back over the bodice to encase it and create a button placket (I’ve already pressed under the back opening edge 1/4″–I also recommend interfacing that placket before this step):

Here’s a close-up of that back opening, folded on itself to encase the bodice:

Now we go to the machine and stitch straight across the front and the backs, backtacking at the beginning and end of each seam:

When I get to the “break” between the backs and the front, I stitch straight across without stopping–a little bit of a varsity move, but I believe in you:

After removing the pins, I serge my gathered seams at this point.  You totally don’t have to, though.  If you wanna get super fancy, you can always bind these in bias tape for a super clean finish, or leave them as-is:
Clip the corners where the bodice and skirt have been attached, at a 45-ish degree angle.  This removes some bulk and gives you a nice, crisp corner when we turn it all right side out:

When we flip the bodice to the right side, the bias tape under the arms naturally rights itself, as well, and is almost in position to stitch down:

Same thing on the back openings, which have created a fast, simple button placket with a clean finished opening at center back:

Once everything is right-side out again, let’s press those bias facings down so we can stitch them in place:

At the machine, stitch a very narrow seam, riiiight along the pressed edge of that bias facing.  Be sure to stitch a curve here, NOT a straight line, so that the underarm fabric remains flat beneath the needle:

The finished product from the inside, with a super clean, light, easy summery feel:

And the outside, crisp and ready to wear:

Feel free to leave comments if I left a step out, and happy summer sewing, everyone!

9 Comments on “Tutorial: Underarm Bias Binding

  1. Thanks for the link! We’d love to see photos of your daughter’s dress, too, once it’s ready!

  2. Oh, this *is* brilliant! It is also the first of its kind I've been able to find! that tricky area is where I have continually had problems with my dresses. Now if I can only actually follow this correctly! :^) I will try…you believe in me afterall ;^)
    Thank you so much. I have 2 unfinished dresses I partially gave up on waiting to get "fixed someday). Sigh

  3. Thank you so much for this clear and helpful tutorial.

  4. My god that fabric is adorable. I can’t stop wanting it.

    Great tutorial for the season, thanks!

  5. Is this the same way to sew a bodice lining in a jumper with a gathered skirt? Instead of bias binding, using a lining, would it be exactly the same method for sewing?

  6. Thank you for this tutorial. I, too, am bookmarking it.
    I made a dress a few weeks ago with bias facing under the arms and around the neckline. I struggled, as I had never done this before. Your directions are very clear and helpful.

  7. love the ease of the tut, however, what I am interested in is the *measurer* / ruler thingie on your sewing arm …. what is it and how can i get one???

    thanks …. darlene