Taming Bulky Seam Allowances - Part 2

Inside a fully fashioned sweater with a very narrow side seam allowance
When pieces of a fully fashioned hand knit or a machine knit sweater are sewn or linked together, the seam allowances can be quite narrow, as tiny as a half a stitch. Now I personally prefer the seams of a fully fashioned sweater to be the width of a full stitch for strength (See above.), but the half-stitch seam allowance is real!

With the cut and sew method we don't usually measure our seam allowances by the stitch, we measure by the fraction of the inch or in millimeters.
Transparent hook cover plate on my machine has lots of markings to line up the seam allowance, I sometimes extend the markings with a strip of painter's masking tape.
As it happens, I happen to love thick bulky sweater knits. One of the challenges when cutting and sewing bulky fabrics is... and you know where I'm going here... bulky seam allowances. Bulk, not from just the width of the seam allowance, but also from the thickness of the fabric. Sure, if the fabric is squishy and you can sew through the fabric easily on your machine, you may not find bulk to be an issue. But if it makes the bulky sweater uncomfortable to wear or if the bulky seam allowances are so thick that their outlines are highly noticeable on the public side of the sweater, then yes, they can be a problem.

There are a few approaches to making the bulk behave -- I've written about at least one before (Yes, there was a Taming Bulky Seam Allowances - Part 1 many months ago.) The other trick I use can also make a difference.

Good Ole Topstitching
You may have come across this situation before: a seam just won't stay flat. You may have tried steaming the seam open as I was taught, when I was learning to sew. Sometimes that helps, but more times than not when you're using a springy sweater knit, steaming the seam open doesn't help enough. (That's one reason why I often steam seam allowances to one side. Added bonus is that if they're steamed to one side, they can be finished at the same time.)

If you think that topstitching will significantly change the look you were going for with your sweater, you'd be surprised. While we know that topstitching usually looks great around the neckline of a t-shirt or a lightweight sweater, you might not want the topstitching to show on a heavier weight sweater. The funny thing is that topstitching isn't very visible with heavyweight springy fabric. I like to think of it as "secret topstitching". The top stitches tend to sink into the fabric doing their job of holding the seam allowances down nicely and keeping the seam flat without the stitches becoming a design element or changing the integrity of the look.

Here are some examples. This is a closeup of a side seam of my Shawl Collar Cardi.

 The seam is flat. And if you're having a hard time seeing the stitching -- good!

And here's a shaped side seam (broken yellow line) on my Fisherman Rib Sweater.

If you're viewing this on a desktop, click to enlarge the pic, and look very closely, you can almost see the 3-step zigzag crisscrossing the seam in this enhanced pic. Yay, secret topstitching! (Edited to add It can be a little difficult if you need to unpick the stitches. Also, stitches do remain visible on plain jerseys even if the jerseys are "sweater weight".)

Not every trick works for every situation, but these are my favorites for bulky sweater knits. Any tips you'd care to share?


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  1. Whoa! That's really invisible!

    1. Yup, the machine stitches just sink in! Forgot to mention that it can be a little difficult if you need to unpick the stitches... Also, stitches do remain visible on plain jerseys even if the jerseys are "sweater weight". I think I'll add that to the blog post.


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