Sewing the Curve: A Princess Seam FBA for Large Busts

Hello, lovelies! Once upon a time, entirely too long ago, I promised you a tutorial on princess seams. Though weddings and holidays delayed my plans, the project still weighed on my mind, because someone needed to document the truth. All those normal princess seam FBA tutorials are helpful, unless you're a well-endowed sewist, then they're like taking advice on snow-skiing from a water-skier. The action is kind of the same, but you're working in much harsher conditions. 

Yeah, that's a lame metaphor. What I'm saying is: adjusting princess seams for a large bust is a weird process, but you can totally do it. I'm going to show you my method, which adds in necessary extra tweaks to the standard process, and has worked for me. There will be lots of photos, exhaustive instructions, and oddly shaped pattern pieces. It's going to be awesome, I promise. Let's do this!

Stage One: Preparations

First off, you're going to need a pattern! Woohoo! Eventually, you will have an awesome dress or blouse from this. For this tutorial, I picked the much-beloved Elisalex dress from By Hand London. It's the epitome of a simple, princess-seamed bodice. 

Once you have your pattern, measure both your full bust and your high bust, as well as your waist. To make the most of those lovely, curved seams, you're going to want to pick your size based on your high bust. This will ensure that your shoulders and upper chest fit in the correct manner, without unsightly gaping. Don't worry if your waist measurement doesn't match up, as we'll also address that during the adjustment.

For me, the measurements were: a high bust of 40'', a full bust of 46'', and a waist of 34.5''. You can see why we need to adjust! If I tried to sew up the size 14, as prescribed on the chart below, the seams would burst apart. 

Once you have picked your proper size, trace off the corresponding bodice pieces and gather your supplies. Personally, I use Swedish Tracing Paper to trace off all of my patterns. It's super durable, but still translucent enough to trace over, and can be sewn up for a fit check. So handy! 

The other supplies you'll need for this adjustment are: tape, a clear ruler, pattern weights, a pencil or pen, scissors, and extra scraps of your tracing paper. 

Before we go any further, take a moment to draw in the seam allowances on your Side Front Bodice. This will make it much easier to visualize your cuts, for the next stage. So, take your ruler and measure 5/8'' (the standard seam allowance, unless otherwise noted on your pattern) all the way around the piece. 

Stage Two: Adding Fullness

Now the fun part: cutting those pieces to bits! When we add fullness to a princess seam, we do the most adjustment to the Bodice Side Front piece, since that's the bit that must curve over your bubbies. For this tutorial, I've marked the side seam with a solid seam allowance and the bust seam with a dotted allowance, so that you can better visualize how this piece works. The curved, dotted bust seam will join with your Center Front Bodice, once we've adjusted it. 

First off, how much fullness do you need to add here? It's easy to find out! Take the difference between your two bust measurements, then divide it by two. Since we'll have two of these seams across your front, each will carry some of the adjustment load. For my measurements, this means I'll do a three-inch adjustment to my side bodice piece. 

Full bust (46'') - High Bust (40'') = 6'' difference

 6'' ÷ 2 = 3'' added to each side

See all those lines in the picture above? Those are our cutting lines, which will help us make this pattern piece larger, and which we're now going to draw onto our piece. They may look complicated, but it's a really easy process, trust me. I'll go through them step-by-step.

Bust Dot: Eyeball your pattern piece and approximate where the fullest part of the bust line is. Draw a dot right there on your seam allowance. In my picture, it's that big black dot.  

Line One: Starting at the waist seam allowance, draw a line up to the bust dot. (Red line)

Line Two: Pick a spot on your armhole 1/4 of the way in from the bust line. Draw a straight line from this point to the bust dot. (Blue line)

Line Three: Pick a spot 1/3 of the way down the side seam. Draw a straight line from this point to the bust dot. (Green line)

Line Four: Measure 1 inch up from your waist seam onto your bust seam allowance. Draw a horizontal line to the pattern's edge. This will be how we later lengthen the piece! (Purple line)

Now, let's make our first cut! Following my red dotted line in the picture above, cut up Line One to the bust point, then continue along Line Two toward the armscye seam. Stop just before the pattern's end, so that you have a small "hinge" to move the piece. 

(Note: In order to avoid confusion, I've only colored your four lines on the original image above. I'll keep color-coordinating their text throughout the tutorial, however, so you can refer back to that image, if you need. They are also numbered the entire way through.)

Now for cut two! Starting at the side seam, cut along Line Three, stopping just before the bust dot. This will give you another hinge point, so that we can move the pattern pieces, without breaking them. 

It's time to add in our fullness. Woohoo! To do this, place your pattern piece onto a large scrap of tracing paper. Using the measurement we made earlier (3'' for me), add in your necessary amount down the length of Line One. You can manipulate both "hinges," in order to keep Line One straight and evenly measured. It looks totally weird, but we're going to fix that! 

Tape all that craziness down!

After taping your new configuration down, cut along Line Four on the seam allowance. Move this down to line up with your other part of Line Four, as shown in the picture above. With your ruler, true up the pattern lines. (Translation: Draw some new lines down to where you moved that piece, so that there's not a weird blank space on your pattern.)

Stage Three: Making Up for All That Fullness

So, we've now added the requisite fullness to our Bodice Side Front, but the pattern piece looks super whack-a-doodle. We have a big dart on the side seam and our armscye is at an odd angle. Luckily, we can fix all of that! This, my dears, is where having a large bust makes this process more fun. We get to do more pattern hacking than the traditional method suggests. We are scissor-wielding rebels!

In order to do all this awesome hacking, cut around your new pattern piece. Place it on even more scrap paper, for these adjustments.

First, let's close that dart, shall we? Draw a line from the lower dart opening (Line 3 beginning) all the way across your pattern piece through the bust dot to the other seam allowance edge. You are not going to follow Line 3, because that wouldn't get you to the bust dot. So, you're making up your own dang line, because you're awesome like that.  

Now, cut along this line to the bust dot. You've made another hinge! Use this hinge to close the bust dart along Line 3, making it reappear in its original state. The arrows above are demonstrating this action. Tape that dart closed and breathe a sigh of relief. 

Warning: If you have a large bust, this part looks ridiculous. Trust me, you're doing it correctly. Your pieces will fold and warp and do weird things, but all that matters is closing that bust dart and getting Line 3 back together. Take a look at my new piece: 

Didn't I tell you it looked ridiculous? Once I've closed the dart, my pattern piece doesn't even lay down! This is where that rebellious line we just drew comes in handy. Cut the rest of that line through the bust dot and side seam. (That's the dotted bit in the picture above.) Your bust seam will now open up like a lovely flower and lay down flat:

This is your almost-completed pattern piece! You are so good at all the things! Huzzah!

Now, an easy part. True up your new bust line, as I have done above. Basically, just draw that curve in, so that your pattern piece connects. Tape all of that down!

You'll notice that your armscye still looks wonky. Let's fix that, too. 

(New armscye close-up)

Fold the armscye corner down, until you get an approximation of the original curve. Tape it down, then true up your corner seam lines. The picture above shows this armscye fold close-up, while the one below gives you the full picture. See how it looks like your original pattern piece again? 

Now, we need to adjust for your waist measurement. Thanks to our bust adjustment, we've also added width to each waist side, as well. To get back to the original waist size, measure three inches (or however much fullness you've had to add) in from the side seam. If your waist measurement did not match the original pattern's, then you can either add less or more, depending on your measurement. I've actually come in 3.25 inches, so that an additional half-inch will be taken out overall. Draw a line up into the seam allowance at your desired waist point. 

From the side seam, beginning at Line Three, draw in a new side seam to this waist point. I've done so with the dotted line above. Once again, it looks weird. We can't cut away a straight line along the side seam, however, because that would take width away from the bust. Starting at Line Three ensures that we maintain our bust fullness, while bringing in that waist seam. 

Don't worry about it. Despite this angle, your side seam will still be straight, because your body is a wonderland. The only thing left to do for this seam is to measure it. Is it the same length as your original pattern piece? If not, add length to both back pieces, as well. For me, this was about a half-inch adjustment. 

Now, cut out your new pattern piece! You've finished adjusting the Bodice Side Front. 

Stage Four: Adjusting the Center Front

So, your Bodice Side Front is adjusted, but that piece still has to fit with the Center Front. Thanks to our machinations, they're currently way our of sync. 

To fix this, measure your Bodice Side Front along the bust seam. (Following the dotted lines above.) Jot that number down!

Now, measure the curved seam of your Center Bodice. Jot that number down too!

Subtract your Center Bodice Length from your Bodice Side Front length. Like so:

Bodice Side Front Length - Center Bodice Length = Discrepancy

For me that looks like:

18'' - 12'' = 6''

I need to add six inches to my Center Bodice, so that the two will become one easily. Draw a straight line across the lower third of your Center Bodice piece, as I've done above with the dotted line above. Cut across that line. 

Separate your cut Center Bodice pieces by your length discrepancy (six inches for me), then fill in with scrap paper and tape it together again. You now have two new bodice front pieces! Well done, you!

They may look like little monsters, but they were created with love and care. Plus, your final result will look bangin'. That's the end goal, right?

On Wednesday, I'll be back with tips on fine-tuning a muslin and sewing Princess Seams. You may still have adjustments to make, based on your individual body type and new pattern pieces, so we'll cover those eventualities. 

Happy sewing, my dears! I do hope this was helpful.

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