Sewing Swimsuit Elastic
Today we're going to learn about sewing swimsuit elastic :) I have a tip for the boys too so scroll on down if you're sewing up some board shorts. And I have a FOE elastic alternative you won't want to miss as well for sewing swimsuit elastic!
Sewing Swimsuit Elastic
As always, make sure to get your Peek-a-Boo Pattern Shop Swimsuit Patterns and KnitFabric.com swim fabric and Board Short Fabric.
What is Swimsuit Elastic
I get asked fairly often what exactly swimwear elastic is so let's start with that :) Swimwear elastic is designed to hold up to chlorine and salt water which for a swimsuit is pretty important. I have used regular elastic in a pinch and haven't had any issues but I recommend sticking with swimwear elastic when possible. The last thing you want is to sew up a beautiful suit and end up with brittle, destroyed elastic partway through the summer. My favorite type of swimwear elastic is the cotton variety. You can get this at Joanns or online.
The other variety is clear and although it works just fine I think it's a bit trickier to work with. It can also tear if you end up ripping out seams... 
Where to Buy Swimsuit Elastic
KnitFabric.com carries swim elastic in 1.25" and 1.5" width as well as the standard 3/8" which is perfect for board shorts! I should also note that for the girls suits 1/4", 3/8" or 1/2" will work just fine so use whatever width you have available. The only thing I might avoid is using 1/2" for the baby sizes of the Coco Cay Tankini or your straps will be super narrow at the shoulders.
Now let's learn to sew that elastic onto the swimsuit!
Some of my patterns have a suggested length and others don't so let's discuss that first. Swimsuits are already quite snug so really the elastic is there to just hold the shape rather than cinch things in. As a general rule, I tug on the elastic just a tad as I attach it but not much. If the elastic is along an arm opening I cut the elastic to the same length as the opening. For most of the patterns, the recommended elastic length for legs/waist is around 90-95% of the length of the opening. To get the best-fit wrap the elastic around your child's thigh, waist, etc. and pull it to the desired snugness and mark off the length.
You can sew the elastic to the leg openings, arm openings, etc. before sewing up your side seams or after. I've done it both ways and you'll find that my patterns use both methods so use whatever you're most comfortable with or what's used in the pattern you're sewing. Applying it in the round leaves a bit nicer finish I think but can be a little bit trickier. If you are applying it in the round start by overlapping the ends and sewing together in a loop.
Line up your elastic seam with the side seam and then stretch it to fit the opening. At this point, I just pin the halfway point in the elastic to the crotch and call it good to go :)
But if you want to be extra certain that everything is even when sewing swimsuit elastic you can also mark of the opening and elastic in quarters and line up those points as well.
Then sew the elastic to the wrong side using your zig-zag stitch or serger
When you topstitch you want to stretch out the elastic just enough that the swimsuit fabric is laying smoothly. You can use a zig-zag stitch or a double needle. I normally just use the zig-zag because I don't like changing out my needle :)
Here's the same fabric with a double needle finish. If you applied the elastic with a zig-zag stitch and are topstitching with a double needle make sure you change your machine back to straight stitch and check the needle position or you will break your needle on your presser foot (trust me on this one...I've broken at least 3 double needles this way). Up close I definitely prefer the double needle finish but once the suit is on it's really not noticeable at all when finish you used so don't panic if you don't have a double needle handy
A great alternative to swim elastic is FOE (foldover elastic) which you can find in tons of cute colors and prints! Here I used it to create the binding and straps on a Waikiki Swimsuit. I didn't have enough FOE to do halter ties so I just tacked the straps down in back instead which also gives a cute finish. To attach the FOE you just sandwich it over the raw edge and topstitch it down with a zig-zag or double needle. It's like an elastic version of bias tape
I think it's really cute and will definitely use it again! If you want to use it as trim on the leg openings or waist of a tankini you'll want to trim 3/8" off first since you won't be turning that edge under anymore.
If you're sewing a pair of board shorts and want a fun finish you can topstitch your elastic! I've done this before on shorts but tend to forget about this nice touch. Sarah from The Crazy Tailor included this on her Cowabunga Board Shorts and I love the professional finish. To create this look just stretch your waistband all the way out so the fabric is laying flat and then topstitch a few rows right on top of your elastic. I generally lengthen my stitch length a bit too. Not only does it look cool but it will keep your elastic from flipping or twisting inside the casing.
I hope you're having fun sewing up some swimsuits this week and I hope this gave you some great tips on sewing swimsuit elastic! For more tips, we have a tutorial on the tips and tricks to sewing swimsuits. As always, check out KnitFabric.com for stylish swimsuit fabric and PeekabooPatternShop.com for stylish swimsuit patterns.
