Tips for Sewing with Swimwear and Knit Fabrics

Sewing with Swimwear and Knit Fabrics

Sewing with swimwear and knit fabrics can feel a little intimidating at first, especially if you're more familiar with woven materials. But with the right tools, techniques, and a bit of practice, you'll find these fabrics open up a whole new world of possibilities. We are here to help you sew a custom swimsuit, an everyday knit dress, or comfortable activewear. Learning how to handle stretch fabrics will transform your sewing experience!

Stretch and recovery: One of the most important things when working with knits or swim fabrics is understanding their stretch and recovery. Swimwear fabric, in particular, is a type of knit that offers significant stretch in both directions (often called 4-way stretch), making it ideal for garments that need to move with the body. Knits can vary greatly, from soft cotton jerseys to slippery nylon spandex blends, so it's always worth checking the stretch percentage and recovery before you begin a project. Hold a swatch between your fingers, stretch it out, and see how well it returns to shape. Good recovery is especially important for form-fitting garments like swimsuits and leggings.

Needle Choice: Choosing the right needle is essential when sewing stretch fabrics. A universal needle might work in some cases, but it can lead to skipped stitches or tiny holes in the fabric. Instead, use a ballpoint needle for most knits, as its rounded tip glides between the fibres instead of piercing them. For highly stretchy fabrics like swimwear or activewear, a stretch needle is even better. It’s designed specifically for fabrics with high spandex content and helps prevent skipped stitches and tension issues. Always make sure your needle is sharp and in good condition, and don’t forget to change it regularly, especially after sewing through synthetics, which can dull needles more quickly.

Cutting your fabric: When it comes to cutting your fabric, precision is key. Knits and swimwear can shift easily while cutting, so a rotary cutter and mat can give you cleaner, more accurate edges than scissors. If you prefer using scissors, make sure they're very sharp and take your time. It also helps to use pattern weights instead of pins, which can stretch or distort the fabric as you cut.

Fabric choice: Choosing the right needle is essential. A universal needle might work for some knits, but for best results, use a ballpoint or stretch needle. These needles are designed to slip between the fibres instead of piercing them, reducing the risk of skipped stitches or fabric damage. Pair that with polyester thread, which has a bit of give and won’t break as easily when the fabric stretches.

Stitch Options: If you’re sewing with a regular sewing machine, don’t worry, you can still achieve great results. Use a stretch stitch, a zigzag stitch, or even a lightning bolt stitch if your machine has one. These stitches allow the seam to stretch without popping. For hems, a narrow zigzag or twin needle gives a clean, professional look. If you have a serger, it will give you beautiful, strong seams and a lovely finish, but it’s not essential.

Stabilisation: Stabilising areas like shoulder seams or necklines can help prevent them from stretching out over time. Clear elastic is a popular choice, especially in swimwear, as it’s lightweight, durable, and holds up well in water. Simply sew it into the seam while stretching it slightly, and it will help the garment keep its shape.

Tension and Pressure: One thing that surprises many sewists is how important the right fabric tension and foot pressure are when sewing knits. Too much pressure and the fabric can stretch out as it feeds through, leaving you with wavy seams. If your machine allows, reduce the presser foot pressure slightly and test on a scrap piece before starting your project. You may also want to use a walking foot, which feeds the fabric evenly from the top and bottom and is a game-changer for sewing stretch fabrics.

Test your settings: Always test first! Before diving into your final garment, use scraps of your fabric to test your stitches, tension, and needle choice. Each knit behaves a little differently, and a few minutes of testing can save you a lot of frustration later.

Sewing with swimwear and knit fabrics takes a bit of patience at first, but once you’ve got the basics down, it’s incredibly rewarding. You'll be able to create garments that not only fit beautifully but feel amazing to wear.