The Magic of Edgestitching

Do you press seams when making a bra?

I’ve been asked this question a few times. You may be surprised to know that iron pressing isn’t necessary in making bras. The only time I have pressed during the making of a bra is when I have made my own underwire channeling. That’s it!

But wait, you ask, how can you get smooth cup seams without pressing?

It’s easy to get into the habit of treating every seam the same way. After all, home sewing instructions place a lot of emphasis on pressing as the way to a truly flat or smooth seam. It’s the key to a professional look and all. And while that is true for many garments, there are other techniques that often get overlooked as being equally important.

Let me explain. Many home sewing patterns place too little emphasis on understitching and edgestitching. Both of these stitch techniques are common in industrial sewing and important to flat seams.

In bra manufacturing, irons rarely if ever touch a bra. One reason is that most bra materials don’t respond well to pressing. Nylon and polyester knits just don’t hold a crease. (Not to mention it’s easy to melt nylon with your iron if you’re not careful! Ask how I know that one.) Unless you are using a woven fabric from a natural fiber, most bra fabrics will flatten and fold with the aid of *stitching* more than the aid of heat.

Let’s call this “stitch pressing”–pressing with a stitch rather than with an iron.

Edgestitching is a form of topstitching in that it shows on the right side of fabric. Instead of just being decorative, it actually serves to flatten a seam and is done very closely to the seam. To edgestitch, you want to stitch about a needle’s width away from the seam, and catch the seam allowance while doing so. A “needle’s width” is about 1/16” to 1/8” (2-3mm) but no more than that.

For bra cups with seams, you have two choices:

1. Turn both seam allowances to one side of the bra cup and edgestitch them down on one side of the seam. This is how I usually sew cups made from lightweight bra fabrics and laces.

2. Open the seam allowance and edgestitch along each side of the seam. This works well if the bra fabric is denser and the seam needs less bulk. Normally, I edgestitch from the right side of the cup but if the seam allowances won’t stay open I often edgestitch from the wrong side of the bra with the seam allowances facing me. This helps to keep those bulkier seams open and truly flat:

While you are edgestitching, use your hands to flatten the seam as it is going under foot. If you gently push the side that you are edgestitching away from the seam, your seam will be flatter than any amount of pressing would achieve—and will stay that way permanently!

Now some of you have wondered whether pressing helps smooth a cup seam that has ripples. As many you know from hemming knits, once ripples are there, they stay there, since the stitching has stretched out the fabric. If ripples are ailing you, I wrote up a few tips for smoother cup seams in this issue of my newsletter.

And p.s. A happy happy spring sewing everyone! I’ve been gardening more than sewing the last couple of weeks but who can resist roses!

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