Hi! I’ve been drafting up a chemise/switch undergarment, and I keep seeing armpit gussets in pre existing patterns. Is there a function to these that is advantageous compared to the modern armpit curve? Gussets seem so fiddly, especially on a machine, and I don’t mind forgoing historical accuracy if mobility isn’t impacted too much.
Thanks!!
The square of the gusset stretches on the hypotenuse bias. The extended sleeve will have that seam there, not allowing for a bias stretch.
I once did the shortcut with sewing up the arm seam, across the triangle, then down the side seam. That’s when I realized about the slight underarm bias actually is helpful when reaching up.
Thankyou! This was exactly the breakdown I needed. :)
❤️ for using 'hypotenuse' in explo! First time I've seen it in the wild since high school geometry a million years ago
That's a great bit of knowledge, thank you!
Great explanation! Thank you
Also in older garmets, they would want to save fabric, so that corner might be added from scraps. A curved piece might use up fabric in a way that you can't make more stuff later on. Make it how ever you want, not one is going to closely checking your underarms gusset :D
Yes! Most people sewed their own undergarments, and rectangular construction is both easier to do and more fabric efficient than any other method.
True. Learn to spin and weave and you rapidly understand why historical patterns were based on rectangles. Curvy fabric patterns were for the rich who could afford to waste fabric.
The underarm gussets can usually be cut from the piece cut out for the head. One could probably get the cuffs out of that odd shaped piece too.
And I hope OP is getting a drink if people are asking to see her underarm gussets!
Mobility is one of the key features of using a gusset, as well as not sitting too close to the skin for breathability.
Imp, gussets are for when you gain 10lbs and the sleeve is too tight. I start with a single piece because I'm lazy.
Imp? I'm sure they can be handy for when you have to adjust your existing clothes, but I like them designed that way personally because it's more comfortable.
I assume imp is a typo of 'imo' (in my opinion) :)
I'm blaming the holidays and less caffeine.... In my projects??!?
I hope so 😅
As well as stretch in the right direction and economic use of fabric as mentioned, a gusset also gives you more anchor points for dress shields (essentially sweat pads!) which can be removed and laundered separately saving on having to launder the main garment so often, an important consideration in pre-industrial life.
Oh wow, never heard of those dress shields, that’s so genius :0 The practicality has kinda romanticised the old construction for me even if it isn’t that useful in 2025 lol, maybe I’ll go all the way and construct it faithfully just for the love of it!
In addition to what others have said, the gusset will fold up into your armpit when your arms are down so it will be mostly invisible. It shouldn’t change the shape of the garment
Edit: No one’s stopping you from setting the gusset by hand if it’s less fiddly that way 😁
You can hand tack and machine finish. That's what I had to do to add a gusset in the crotch of a pair of pants I just altered
For an undergarment: The gusset creates additional range of motion without pulling on the bodice. This means that a gusseted arm may have a much tighter fit around the shoulder/upper arm, making it a sleeker fit underneath another garment.
For a generic garment: if the fabric you're using has very little bias stretch, a gusset becomes much more necessary. It's more common in older designs because most fabrics contained zero spandex / elastane.
I made a pair of pajamas with a sleeve curved like that. The armpit tore out. Use the gusset.
It was more to not have scraps of fabric. Curves make it hard to use everything. Broken down, the curves are kinda like a gusset. I think makes for cleaner looking arms, as theres a seam to help it fall and bend, but if you really need to you can replace it too.
Edit. Welp everyone basically said all that already. Id like to add in curves are just a pain to sew.
From a design standpoint, gussets can be an opportunity for using combo fabrics or cross grain cut fabrics. For instance: rib knitting, pleated taffeta, and stripes cut in different directions.