Swimsuit Sewing – Part I

February 22, 2012 in Projects








I’m just going to admit that I am by no means an expert on making swimsuits, but I do enjoy the challenge for myself and people I know well (meaning I don’t just make swimsuits as a part of my business or for just anyone). So, it’s a project I can have fun with and they don’t take that long (especially after you’ve made a couple)! They can also be a lot cheaper!! You can use general sewing thread. You’ll want to make sure your machine is in good shape so you don’t get missed stitches and try out a stretch needle! If you have extra advice, please leave a comment!!

This tutorial is to walk through making a 2-piece swimsuit. Part I will be on making lined swimsuit bottoms and Part II will be on a swim top. I used Mccall Pattern 5400 for the bottoms (the above left picture is a pattern picture; there is a thinner and wider waistband; I did the thinner waistband). The fit seemed to be pretty good, but, I like to make a mock up first (because they don’t take that long) with a cheaper solid fabric that I got with a coupon (if it fit’s, you get an extra pair of bottoms)! So after I made my mock up, I found that I could cut a 1/4″ from the front and back at the crotch to tighten it up a bit around my bum. So, now, I have a swimsuit bottom pattern that will fit every time I make it (that is if I’m using the same fabric type – knits stretch differently and will fit a little differently, check out this site for more information). Let’s jump in…

 1. Pin and cut out pattern pieces (front and back bottoms) on the fold. Because of the design of my swim fabric, I placed my pattern accordingly to capture the design that I wanted my finished bottoms to display.




2. Here are my front and back pieces cut out. I like to completely line my bottoms; this is different than most patterns; they usually just line the crotch. Lining the entire bottoms is just as easy and I like the strength and fit of it as well. So, you can self-line, like I did, where I just cut out another front and back out of the same/extra fabric or you can cut out the 2 extra pieces out of actual swim lining. I haven’t noticed a difference, I like both. In this case, I used the same fabric. Mark all relevant pattern marks (most importantly the marks for elastic).




3. Remove pattern and open: Here is the back (top) and the front (bottom) of the bottoms opened up (my lining looks identical to this).








4. Pin the center front crotch to the center back crotch.







This is showing up close of the last picture (it’s flipped, FYI).





Next, you’ll have to stretch the back piece (at the crotch) to fit the curve of the front piece. Notice that they do not match up exactly (where my index finger is). The M5400 pattern says that you’ll use 5/8″, so it will match up right at that line. So, after you’ve pinned the center (above) and then pull the sides as shown (by my index finger to the left). Then, stretch between your center pin and your outer pin and pin in between to allow for even distribution of the front to the back. See picture below to see how the entire crotch is pinned.



5. Then, pin your side seams.






This is a close up of the side seam, notice the un-alignment of the side seam (this is what I was trying to explain also with the crotch seam). This allows for the proper amount of seam allowance.




6. You’ll do the same pinning for the lining (remember my lining is the same fabric as my outer).

7. Sew a 5/8″ seam allowance on the outer and lining crotch and side seams. You’ll need to slightly stretch the crotch to fit the back fabric to the front (this also allows for a little bit of stretch when worn). You’ll also want to stretch the side seams a bit as you sew. I sewed my seams twice for extra support, stretching a bit again as I sewed.



8. I then, cut all of my seam allowances in half to take out some bulk.







Just a little FYI, your bottoms may do this a bit (where my finger is pointing) at the crotch seam. Don’t worry, most of the time it will stretch and lay just right when worn. If you’d like to try on to test out fit, you may, but remember that the elastic and seam allowance will affect this anyway (that’s why I recommend making a mock up first to alter your pattern for better fit).



9. Now, turn your outer fabric right side out (below in picture) and your lining fabric keep inside out (above in picture). Place the  lining inside the outer layer, so that your wrong sides will be together, matching evenly, your waist and let holes as well as your side seams and crotch seams.






10. Then, you’ll want to pin them evenly at the waist and leg holes. (Reminder: where my finger is, that is my lining). (I like to set my pins back a bit because the next step will be to serge the leg holes and waistband. If you do not have a serger, try zig-zagging your two layers together). As I pin, I like to push one seam allowance completely forward and one completely back (rather than opening up my seams, they aren’t quite as strong if opened).



This is just a close up.







Here they are completely pinned at the leg holes and waist.







Here is a close up pinned at the leg holes.






11. Serge your waistband and leg holes to keep both layers together and for a professional look! (As I stated before, try zig-zagging your edges to keep it together, this type of fabric won’t fray; zig-zag also allows for stretch).




12. Cut, mark, match up and pin elastic according to your pattern. Match up elastic with the marks on your fabric and pin even with the edge of the leg holes and waist on the wrong side, or lining side (so, it will be inside out)! Then, stretch in between pinned and pin again in between and so on until you feel the elastic is evenly distributed.


Here is a close up.







Another close up.






13. Zig-zag sew your elastic on, stretching it to fit. (The zig zag on my Baby Lock sewing machine was set at 4.5 width and 3.5 length).






Completely sewn.





14. Last step already! Now, you can cover stitch if you have that capability, like my Baby Lock Diana Serger, or skip down a couple pictures to see zig-zag by sewing machine. Shown right: I pulled my cover stitched tail out and clipped so that I could place my bottoms flat underneath the serger foot as sewn below.


 So, you’ll turn your bottoms right side out and fold your waist down one elastic width (shown in your pattern as well). Shown in the picture (left), I have folded my elastic under and pushed the waist underneath (I did have to alleviate some presser foot pressure as it is kind of thick). I also started just after a side seam and I lined up the edge so that I’d be stitching close to the bottom edge of the elastic (so that it won’t roll out when worn). Just an FYI, do some test stitching before stitching on your actual fabric. Also, I noticed that I had to go quickly over my seams so that it wouldn’t get stuck causing me to have to clip it out of the machine. So, hold tight at front and back when you approach a seam and don’t stop or slow down while going over it.



Showing the cover stitch on top here.







Here is the back side. I have a serged edge, a zig-zag from sewing my elastic on, and a cover stitch from my Diana Serger.




The cover stitch looks so awesome and professional!





Finished product!






Here I zig-zagged instead of cover stitching. My Baby Lock Sewing Machine was set at 4.5 stitch width and 3.5 stitch length (test what you like before sewing on your actual garment).












Finished product with a zig-zag finish rather than a cover stitch.





Have fun! Let me know if something doesn’t make sense or add a comment if you have any pertinent tips for sewing swimwear fabric!

2 responses to Swimsuit Sewing – Part I

  1. Ummm, awesome!

    • Thanks :D It’s probably the best one I have ever done and the cutest…and I love the cover stitch on it!!!