I'm a sewing enthusiast in Beacon, New York, with a love of all things retro. This site is all about tutorials, tips, inspiration, and lots of spirited discussion about sewing as it relates to fashion history, pop culture, body image, and gender. My first book, Gertie's New Book for Better Sewing, is now out from STC Craft/Melanie Falick Books! Also look for my line "Patterns by Gertie" from Butterick.
As promised! This technique isn't difficult, but it has a few parts, so I'm going to break it up into three posts. Part one is modifying a dress back pattern so it's the right size to be shirred with elastic thread. We're going to be talking about strappy and strapless patterns, so no full-coverage dress backs. (Note: there is a way to shirr a full coverage dress back, and that's to change the style lines so you have side panels underneath the arms, and then shirr those.) Note: the only special supply you'll need for the whole tutorial is elastic thread. It's widely available and made by a variety of brands, including Gutermann, Stretch Rite, Dritz and Designer's Choice. It generally only comes in black and white, so choose the best color for your fabric.
You can modify a basic dress back bodice like so. The green is your new style line. (Note: CB is center back and SS is side seam.) Pretend these sketches are good and they weren't done on an envelope, okay?
Important: don't forget to add a seam allowance at the top of the new back pattern piece.
If you're using a basic sloper or simple dress pattern, you'll also want to change the front. You can do sweetheart:
Or a simple straight front:
Isn't patternmaking fun? No matter which shape you do, make sure your front and back side seams are the same height so they match up when you sew them together. They should form a smooth line, rather than dipping down into a v-shape. Also, always do a test run of the front, even if it's just a tissue fitting.
We'll be shirring the whole back, rather than side back panels, which is often what you'll see on vintage sarong dress and rompers. This just keeps it simpler, but you can certainly break up your back into panels and shirr only the side panels.
With a fitted-waist skirt like a circle skirt or pencil skirt (or even fitted shorts for a romper), you'll still need a zipper. But we WILL be adding elastic shirring to the top of the back skirt, so it will stretch with the back bodice. More to come on that. (If you make a gathered skirt and elasticize it, you won't need a zipper, but I'm not focusing on that technique here.) I highly recommend doing your zipper center back. (This is the sleekest, flattest zipper application for this kind of dress. A lapped side zipper gets kind of ruffly and adds width to your side. ) This means you'll have seam allowances at the center back for the zipper. Add them if your pattern doesn't have them already.
Now, close up the back darts and trace the pattern. It's now dart-less, which is what we want.
Now you need to figure out how much extra width to add to accommodate the shirring. It's a process of trial and error, really. Shirring reduces the pattern piece width by half. But you can't just double the pattern width, because you want the elastic to be snug on you, so it stretches a bit and conforms to your body. Make sense? The first pattern I did this with, I slashed and spread to add a bunch of inches to the middle of the piece. It was way too big. (Which isn't a big deal, I just made big seam allowances in the back and then trimmed them down.)
The next one I did, I took a simpler approach: adding just an inch to each side of the pattern piece. Make sure you don't make the piece taller in the process, since it still needs to fit in to the front pattern piece at the side seams. The green shading below is the extra width.
This approach worked really well, though it is very snug. It's bombshell-fitted, which is exactly what I was going for in the Shaheen-style dress I was making. If you want your dress to be a little looser, add 1-1/2" inches at each side of the back pattern piece.
Next, cut two of your modified back pattern piece in your dress fabric.
Tomorrow we shall shirr. Shirrly we shall! (You must excuse just one bad "shirr" pun.) There's video and everything. On Wednesday, I'll show you how to sew the shirred piece into dress.