How do you attach elastic to a bathing suit?
How to sew elastic onto a swimsuit edge. - YouTube
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For best result, dampen a cloth and place over the elastic waistband. Then, iron for 10 seconds, let it sit for 10 seconds and repeat the same steps for about 5 minutes. Doing so continuously will help the pants fit more snug, as the elastic heat up it will gradually shrink more and more.
First, you can make an elastic waistband for your swim bottoms (via What Wear Fit). Along the waistband of your swimsuit, cut a lining to install an elastic band. Cut the elastic band shorter than your waistline to create a tighter fit.
DIY Sewing Alteration: Women Swimsuit to Tween Size Tutorial
How to Replace Elastic Waistbands - YouTube
The elastic material might even break. This happens when it becomes too dried out, and as of now, there is no known way to revitalize the elastic once it gets to this point. Unless you want to wear the now saggy clothes, it is time to replace the elastic strips.
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Place the patch of fabric behind the tear, on the inside, and sew it on iwith whatever means you have. But for the best results, Douglas recommends that you'll use a (serger) sewing machine, a stretch stitch and a stretch thread: A sewing machine.
Use swim-specific elastic.
All swimsuits require elastic, but you want to avoid using standard polyester elastic because it will not hold up to chlorine and salt. Instead, look for chlorine-resistant cotton or rubber elastic. Make sure it's labeled specifically for swimwear!
What kind of thread is used for swimsuits?
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.