I’ve been making my own swimsuits forever – because I can’t buy one that fits exactly the way I want it to (you know, that flat bottom with skinny legs!). Many years ago I found this Kwik Sew pattern that produced a great swimsuit – 2 hours from start to finish. The only challenge was adding the elastic to the arm/neck and leg openings. I’ve always done it using a zigzag stitch on my embroidery machine but it’s a fiddle getting the slight amount of fullness distributed evenly. Takes quite a bit of pinning and an awkward hand position as I’m sewing the elastic in small segments. Once the elastic is in, the top stitching is no problem.

I got a new serger a couple of weeks ago (a Baby Lock Evolution) and I went for my new owner lesson. I explained to Heather, the teacher, I’ve been using sergers for more than 40 years, I didn’t need help threading the machine — what I wanted to learn was how to use the serger to apply elastic to swimsuits. I had come prepared with swimsuit fabric scraps and some elastic for us to try this out. So she found the appropriate elastic foot for my machine and we got to work.

Here’s the challenge – the arm/neck opening on my swimsuit is 120″. For a comfortable suit I need 106″ of elastic so the amount of gathering is minimal, but I still need a bit of fullness to be accommodated in the elastic. There are two ways of achieving that gathering – with the differential feed and with the knob on the elastic foot itself. The instructions suggest the maximum amount of gathering with the differential foot – we tried that – way too much gathering; we adjusted the differential feed back to normal and just used the knob on the foot to adjust the tension on the elastic – it didn’t need much.

When I got home I started experimenting – the ratio of fabric to elastic: 1.13 so I cut a strip of fabric 15″ long, a strip of elastic 13 3/8″ (plus 2″ for the initial feed – marking the 2″ mark with a permanent marker and positioning the elastic with that mark at the needles leaving me 13 3/8″ of elastic to be sewn to the fabric edge). My goal was to attach the elastic to the fabric edge (using the 4 thread overlock stitch) and have fabric and elastic come out about even. It turned out that I actually needed a negative differential feed setting – 0.8 seemed to work well and very little tension on the foot knob. It took several tries to find the amount of gathering I was after but I thought I was close enough so I decided to try a swimsuit I had cut out and partially assembled.

My usual way of sewing up a swimsuit is to sew the side seams, the center back seam, the should seams and the crotch. To apply elastic with the serger I needed to leave the back center seam and the crotch seams open so I could work with the openings as flat fabric. The first swimsuit I worked on required a LOT of patience — I stitched the elastic into the neckline but the fabric gathered too much; I removed it, all 106″ of it, and tried again. Second try I didn’t have enough tension on the elastic itself and so I ran out before I got to the end of the fabric; again, I removed the elastic, readjusted the tension on the elastic foot and tried a third time. It actually took a fourth try to get the tension more or less right but in the end it worked.

The leg openings required a wee bit more tension — the first leg opening turned out nicely on the first try but the second was way too gathered. I ripped the stitching out and tried a second time — it was better (good enough to live with).

I serged the center back seam and the crotch, then turned the elastic and top stitched it in place — voilà I had a wearable swimsuit (I wore my new suit to aquafit class yesterday and a couple of gals commented favourably on it).

Having finished one swimsuit successfully I cut out a second and sewed it up. This time the elastic in the arm/neck opening went well on the first try, as did the leg openings. Serging the center back seam presented a bit of difficulty because I had to start the stitching on a double thickness of elastic (on my next swimsuit I will use a starter strip of double thickness of fabric to get the seam going) but a second try was successful. Again, I sewed up the center back seam, the crotch, turned and topstitched the elastic and swimsuit #2 was done!

What a difference this foot has made to the process of swimsuit construction – the elastic is easily applied and the whole production from cutting out the fabric to finishing the sewing took about two hours. The elastic foot was definitely a good investment!