TLDR; stays fitting is WEIRD.
So I’m using this 1760s/1770s half boned stay pattern from La Couturière Parisienne.
First, printed out the pattern without changing the sizing at all. Using some math about how big the pattern waist was compared to mine, I printed it out again at 200%.
After doing that, the back looked fine, but the front looked kinda small. Measuring the bust and waist, I then was sad. The waist was fine – a few inches smaller than mine, maybe a leetle bigger than I wanted given this would have a lacing gap, but whatever.
The bust though – yikes, I calculated I would need like 3-5 inches more room. This sounded really weird, because it’s not like my bust is dramatically bigger than my waist. Like, in modern patterns, I usually have to size up for the waist, and then the bust is too big, so this was super weird.
But numbers! I listen to numbers! So I eyed my patterns, tried to figure out where to slash and spread them, and added a bunch on to the top. And then the pattern looked heinously weird. Like, holding it up to my dress form, I could already see I had added too much to the bust. (My dress form is bigger than me all around. So if the top of my pattern was bigger than the front-to-side measurement, this is a Problem).
So I said screw it, undid all my changes, and cut out the pattern as is.
This… fits? The back is an even lacing gap? The top is a little short, even on short-waisted me. As usual, I have to futz with the armscyes. But this is almost a perfect fit. So uh, if you are 4’11” with a short waist, you can pretty much print out that pattern and have it fit you on the first try.
I guess stays compress your bust enough that there is less of a different between bust and waist measurements, compared to something like Victorian corsetry. Still, super weird.
Made a few tweaks around the armsceye, I cut a second mockup out of muslin (which has slightly less stretch than the who-knows-what fabric I used for the first). Also took a bit out of the back, since I wanted a bigger lacing gap.
I’m still in shock that this worked. The only change I made between this and what I started cutting, is adding a bit more on top for coverage, since I can always cut it down later.
Note that I made these mockups out of one layer of muslin, and no boning. It’s totally possible, as I learned in a corset class.
1) Expect to see wrinkles at the waistline, since fabric will go to the easiest point. These will go away with boning.
2) You still want an even lacing gap
3) Hoist up the bosom to get a real idea of how it’s going to fit once boned. No, I didn’t get any photos of that.
4) I left this unsewn below the waist at the sides, since I know this will be cut into tabs in the final version.
Still have no idea why this pattern fit so well, but LA LA LA I’m off to cutting and am done with nasty fitting!