How to sew bathing suit fabric – 10 best tips & tricks

 There are a few things that tend to terrify sewists. When they start out, sewing stretchy fabrics seems outright impossible. (If this is your case, make sure you read my post on how to sew knits and other stretchfabrics perfectly.) For the more ecologically-minded who want to start sewing cloth diapers or cloth menstrual pads, sewing the waterproof PUL fabric is a nightmare. (I’ve put together my best tips for sewing PUL withoutproblems in this post.)

For the apparel sewist, there are a few scary types of clothing. Coats. Jeans. (I got over my fear of sewing jeans a couple of years ago when I tested the Birkin Flares pattern.) Bathing suits.

 ost apparel sewers are used to sewing stretchy fabric, but bathing suitfabric is a beast of its own. It’s REALLY stretchy and, as bathing suits fit skin-tight, the seams need to be able to stretch a LOT. The second scary thing about bathing suits has to do with the general fear women have of showing off their bodies for what they are.

I finally got over this fear this summer and learned how to sew bathing suit fabric, sewing myself and my kids swim caps, bikinis and one-piece bathing suits. And guess what? After learning a few tips andtricks, it isn’t anywhere near as scary as I thought it would be! I wish I had started sewing swimsuits sooner!

Have you been considering sewing bathing suits for you and your family? Are you a little terrified of trying? Check out my ten tips for how to sew bathing suit fabric, and you’ll be making your own DIY swimwear!

10 Essential Tips to Perfect DIY Swimwear

1. Use the right fabric. Bathing suit fabric is basically a lycra (spandex) fabric that stretches a lot and dries quickly. It doesn’t get very wrinkled, so it’s easy to care for and sew. I couldn’t find any swimsuit fabric in local fabric shops, so I bought a selection of matching colors and prints on Amazon so that I could mix and match them. I purchasedred, purple and black solid colors here* and a turtle and a hibiscus print here*. There are a lot of other online shops carrying bathing suit fabric. Look here for a wide selection on Etsy*.

Most bathing suits have a lining, which requires a different fabric which is lighter and more stretchy. I bought this black lining fabric* (seen above on the right) and have used it for all the swimswear I’ve sewn. If push comes to shove, you can just use the same bathing suit fabric as a lining layer, too, but I prefered having the right type of fabric.

2. Get your stretch type straight. Swimsuit fabric can have 2-way stretch or 4-way stretch. 2-way stretch fabric stretches horizontally, from one selvedge to the other. The stretch always goes around the body. 4-way stretch fabric stretches equally well both horizontally and vertically, meaning that the garment will stretch around the body, but also up and down the body. It’s really important to use the type of stretch fabric that the pattern calls for.

3. Use ballpoint pins and stretch needles. I have been using these ballpoint pins* for years and love them. I use Schmetz brand 90/14 stretch needles* for sewing bathing suit fabric.

4. Use polyester thread. Cotton thread snaps much more easily than polyester thread. This is why it’s always best to use a poly thread when sewing bathing suits, which are meant to be stretched a lot. My favorite is GutermannSew-All polyester thread*.

5. Use an overlock machine. The overlock machine, also known as a serger, uses three or four threads for an entwined stitch that is VERY stretchy, and so perfect for swimwear. I use my serger (I use an Elna664 pro*) for ALL bathing suit seams except for basting and topstitching. In some cases, such as when you sew elastic to the fabric, you will want to disengage the overlock machine’s knife.

6. Use a stretch stitch or the zig zag stitch. If you don’t have an overlock machine, you will have to use your regular sewing machine for all steps. This isn’t a problem because there are a lot of different stretch stitches you can use, such as the triple straight stitch (#3 above) and the stretch stitch or lightning stitch (#4 above), which are good when you need a straight line of stitches. When that’s not so important, such as when basting or joining elastic to the fabric, I suggest using the classic zig zag stitch (#5 above) or the triple zig zag stitch (#6 above). You can find out more about how this stitch works in my zig zag stitch lesson. For my bathing suits, I preferred using a serger for all inside seams and a zig zag stitch for everything else.

7.Use a double needle for topstitching over few layers. The double needle is great for all stretchy fabric and creates the same look as a professional coverlock machine on the outside. I suggest the Schmetz 90/14 Stretch Needle*. You use it with a regular straight stitch, but the zig zagging bobbin thread on the wrong side of the fabric lets it stretch, making it great for topstitching. I love this look, but I honestly had a hard time using it when there were too many layers of fabric, so I actually ended up just using a zig zag stitch for almost all topstitching, even though it doesn’t look as professional.

8. Use a walking foot. This special foot is one of my absolute favorite sewing tools. It has its own feed dogs that work with the sewing machine’s feed dogs. Having feed dogs both above and below the fabric means that it moves bulky, slippery or otherwise difficult fabrics under the sewing needle evenly. You can read more about this wonderful machine foot in my walking foot sewing lesson. I kept it on my machine the entire time that I sewed anything with swimwear fabric, and it made life SO much easier!

9. Use the right stitch width and length for basting andstitching. The stitch length needs to stay relatively long to give more stretch. The width depends on what part of the garment you’re sewing. I preferred using a zig zag stitch with 2 width and 3 length for basting, and a zig zag stitch with 3 width and 3.5 length for topstitching. But try different combinations to find the best one for you. Which brings us to #10, perhaps the most important tip of all:

10.Practice makes perfect! Try different fabrics, stitches, needles, machines. Use scrap swimsuit fabric to test out different stitch length/width combinations. Fold the fabric to practice working over various layers, or even sew some seams and fold those over to see how different methods sew over those more bulky areas. This was how I decided that I didn’t want to bother with the double needle, because I couldn’t get even stitches when sewing over bulkier areas.

Sewing bathing suit fabric is differentfrom sewing other fabrics and you need to test everything out over and over until you find what works for you. And at that point you’ll see that it’s actually pretty easy and you’ll be ready to start working on your bikinis, bathing suits and swim caps!