So a little latter than planned,, here’s the second instalment of the sway back adjustment I promised. You can read part one here. But just to recap quickly on where we got to…loadsa fabric in the back for me. Pinned one horizontal tuck….didn’t quite take care of it*. Pinned a second horizontal tuck further down…part one of problem solved… *(worth noting that I have omitted the back darts. This will have had a small impact on how much I had to pin out)
Then with the toile taken apart and pressed flat, I’d marked all my adjustment lines in pen and evened them all out…
Soooo…moving forward, the next step was to make those adjustments to a paper pattern. To do this I laid out my toile back piece and laid some swedish tracing paper on the top. Making sure everything was flat and weighted down…
Then traced off my pattern piece including all the markings where I want to remove the excess fabric in the back…
If you consider those markings as a dart , (essentially it’s the same structure) You could just treat those lines as dart markings and fold out the excess. I’m using a slash and overlap technique here. Slice along the top dart leg. (Apologies for the poor lighting in these pics. Twas a very grey day indeed!) I should technically have left a little pivot/hinge at the narrow end. But I just sliced right through because I find the hinge thing fiddly.
Then overlap the pieces so that the bottom dart leg lies on top of the cut edge (or what was the top dart leg)…
Stick in place with masking tape and in my case, repeat for the second tuck. It’s at this stage when lined up against the straight edge of a ruler to mimic a straight CB seam, that you can see exactly the effect it is having. THAT my friends, is how curved my back is!! Crazy!! I actually held that up side on against the profile of my back and it totally is!
So. Hopefully up to this point this is all making sense. But here, for me is where I slightly depart from fully understanding the “why” of each stage and just start trusting that this works. Even though the next couple of steps, to varying degrees, may seem a little counter intuitive.
So I have my altered pattern. Now it’s so skewed that I need to “true” up various points to make it a useable pattern piece. I’ve stuck my pattern piece to my worktop with super wide masking tape, along the CB seam here. It stops it shifting around and gives me something to draw my new lines on. So firstly I want to square down from the neckline to the hem to give me a straight CB seam again. So here’s the counter intuitive bit right? I just curved that back seam. Why do I want to make it straight again? Well, my logic is telling me that the aim is not to curve the CB to echo the curve of your back but to shorten the CB and remove excess fabric. (The curve in the pattern above is a bi product of that rather than the actual aim) You still need a straight CB. You may also remember that after I’d taken the tucks out of my toile, the back became tighter. This step also adds some width back in at the CB to combat that….
The red dotted line is the outline of the altered pattern piece. The straight solid pencil line is my new CB seam. You can see that it’s incrementally adding width back in down the length of the CB. I would imagine, relative to what we’ve taken out, but, in a different place. I’m beginning to understand this adjustment as a “redistribution” of the fabric to some degree if that makes sense? But please chime in if you can explain with more clarity!!
Below is the hem and CB seam. Again, we need to square across from the side seam to the new CB seam. You can see the red dotted line shows how much the adjustment has skewed the hem. So by doing this, you can see we’re adding length back at the bottom of the CB seam (ie at the hem). This is the bit that seems the most counter intuitive. If we want to shorten the CB seam to counter the sway back issue, why are we lengthening it again? Again, my reasoning is telling me that we are redistributing that excess length that we took out. Moving it from where it’s not needed to somewhere else. But interestingly, when I measured it…it doesn’t add up to the total length of the tucks that I took out. And when I compare the length of the new CB to the one on the original pattern piece…it IS shorter by about an inch…despite the fact that it doesn’t look that way once the toile is reassembled with the new back piece! Weird right??
The final step is to redraw the side seam. With the original laid on top and matching the underarm and hem points, you can see how the adjustment has altered the shape of the side seam too.
Simply trace along the edge of the original pattern piece to get the side seam shaping back to what it should be. You can see that this will be removing overall width. So again, my reasoning is telling me that what we added in width when we squared the CB seam was more than what was necessary to bring the pattern piece back to it’s original proportions. So shaping at this side seam and removing a small amount of width in the process, is in theory bringing everything back into proportion in relation to the original pattern. I am not stating this as fact. This is me thinking out loud & trying to get my head around how this adjustment works. I know that it does work. But the geek in me needs to know why and how too!
With the new side seam drawn you can now see what will be removed from the side seams…
Now this is not a great picture (below) and if you’re viewing it on a mobile device you may not be able to see the detail. So take a look on a desktop if you get the chance…
My new pattern piece (above) with all the adjustments complete but before I cut it out. You can see the curved red dotted line at the CB and hem and the cut edge at the side seam. That’s the outline of the skewed pattern piece once I took those tucks out. The solid pencil lines are the new outline once I’ve done all the “trueing” and reshaping. You can see that a big chunk of width was added in at the CB when it was squared down, (look at the distance between the red dotted line and the new CB line) but some of that has been taken out again at the side seam when I reshaped it. (Look at the distance between the edge of the pattern and the newly drawn side seam).
Now, here’s the interesting part if you like a geek out! It may hold some clues as to why this works! With my new pattern piece all cut out, I laid it over the piece from the original toile. Although at first glance the piece appears to be the same shape as the original….look what happens when I line it up at the shoulders and armholes!!
Then look what happens when I line up the side seams…
WEIRD right??? The angles are totally different in relation to the original! Now, while I will not pretend I can thoroughly explain why this works, comparing those two pattern pieces and reasoning out what we’ve done, I’m forming a blurry idea of what’s going on in the big sway back mystery. It seems to me that the process is a combination of redistributing length (and consequently width) away from where it is not needed, and moving it somewhere else; and overall, reorientating the pattern piece.
Having said that I still don’t fully understand the why and how (mostly in relation to choosing where to square off from and to and why we add length back in at the hem); but I can prove to you that it IS what you do and it DOES work, because, well, look! I did it….and it worked!
I may revisit this on scale paper cut outs in an effort to understand it fully. Because it seriously bugs me that, although I know it works….that’s not enough! I need to know how and why. And this time I am going to make copious amounts of measurements and get all mathematical on it’s ass. If I have a eureka moment, rest assured I shall share because I know there are other geeks out there for whom “yes….but WHY?” is as common a question as it is for me. But for now, this is how you do a sway back adjustment!
A really good tute here just in case my pics don’t fully give you the full idea, btw 🙂
And in the meantime, if you have the ability to clearly explain what is going on with a sway back adjustment and why it works, or if you know of a blog post somewhere that clearly explains, not the how….but the why, then pleeeease tell! I’ve searched and searched the interwebs to no avail. Lot’s of “how to’s” out there. And I’m all like, “yes, yes , yes…but WHY do we square up here and not there and WHY do we add back length to the CB if we’re trying to shorten it???”
Yes, I am the adult version of that annoying child that repeatedly says “yes Mummy…but whyyyyyy?” until mummy screams and as a mental breakdown. 😉