Pendrell Sew-Along #5: Princess-Seam FBA (Full Bust Adjustment)

Here we go: Full Bust Adjustment time! Today I’ll show you how to adjust a princess seam blouse for a full bust.

This is the method shown in Fit for Real People, which you may have seen before. It comes highly recommended by sewists with fuller bustlines!

This pattern adjustment is a little tricky, but it’s a great way to adjust for a fuller bustline while keeping the shoulders and armhole intact. Otherwise, if you just cut a larger size all around, your blouse will be too wide in the shoulders and gaping or pulling in the armhole.

Catch up on the first five sew-along posts here!

• Pendrell Sew-Along #1: Prewashing your Fabric
• Pendrell Sew-Along #2: Measuring and Choosing Your Size
• Pendrell Sew-Along #3: Shortening the Blouse Length

• Pendrell Sew-Along #4: Altering The Hip and Waist

FBA Fine Print: I’ve never made this adjustment for myself, or for anyone else. I’m hoping the FBA experts will jump in with their comments and opinions, which would be wonderfully helpful! I’ll also include links to other FBA tutorials so you have as much information as possible to make your own adjustment.

You’ll need:

• Your pattern pieces: Front (1) and Back (2), Side Front (7) and Side Back (8)
• Yourself! Wear the bra you’ll likely wear with the finished blouse.
• Tape measure
• Ruler
• Pins
• Scissors for cutting paper
• Scotch tape (I am out of scotch tape, so I’m using clear packing tape…)
• Pencil and eraser

My Imaginary FBA

As you might know, there is no need for a FBA in my world. So for today’s demo, we’re using Diana (our dress form), dialed up to a fuller bust – as I can’t demonstrate on myself! Diana’s newly enhanced bustline is now 98cm (instead of my usual 81cm) so we’ve got a bit more to work with here.

First, let’s determine how much to add. (If you already know how much you want to add, skip to the next step below, where we draw 3 lines on our pattern piece.)

There are two ways to figure out how much to add: either by tissue-fitting, or by making a muslin. Since I’m not making a muslin, I’ll show you the tissue-fitting method, but the same idea applies if you’re working with a muslin.

Take your pattern pieces and pin them together along the seamlines. Make sure to pin using actual, 5/8″ (1.5cm) seam allowances. Pin the seam allowances outward, like I’ve done below:

Pin all the way along the seamlines, as shown.

Now we’re going to try the tissue on Diana. If you’re following along at home, you’ll want to try it on yourself. That’s the best way to follow your own curves! Unless you have a custom-made dress form, and even then you’ll still want to try it on your own body to be certain it fits.

What we’re doing here is fitting the half-shirt on Diana, lining up the centre back and centre front. Now likely, your centre front won’t meet the dress form’s centre front, at the bustline. That’s why we need the FBA!

See, in the photo below, I’m demonstrating with my left hand where the centre front line should be. You can see that the tissue doesn’t quite reach across the body.

In order to make the pattern tissue meet at the imaginary centre front line, we’ll unpin the princess line right over the bust. We’ll open it up and spread the tissue, and that will help us figure out how much to add.

NOTE: if you’re following along with a muslin, the same theory applies. Just unpick the seam allowance over the bustline, instead of spreading the tissue.

Gently unpin the seam allowance over the fullest part of the bust. Pull the front panel so that it lines up with centre front. If you’re trying this on yourself, pin the centre front part to your bra or a camisole.

Next, measure the opening. (Make sure to fold back the seam allowances, and don’t include them in your measurement.) That’s going to be the amount of our FBA. Diana needs a 1″ FBA so that’s the measurement I’ll demonstrate with.

In Diana’s case, she only needs an additional inch even though I’ve added 17cm to her bust measurement. Why? Because this blouse has plenty of ease. It’s supposed to be roomy! That’s why some of you who usually need a FBA, won’t need one with this blouse.

Grab your side front pattern piece and draw 3 lines:

Line #1: Draw a line UP from the hemline along the seamline, so 5/8″ (1.5cm) from the cutting line. Stop around the full bust point – if you’ve made a muslin you can find this point easily! For me, I’m going to look for the curviest part of the seamline as my full bust point.

Continue Line #1 from the full bust point and connect it to the armhole. We want it to be 1/3 of the way around the armhole, so it’s easier if we start drawing our line at that end. first and then connect it to the first, long line.

Line #2: Draw an angled line where a bust dart would be, like mine below. Mine looks like it’s halfway between the first two lines, angled towards the sideseam.

At this point I realized it was a good idea to draw in my seamlines. Draw in your seamlines, 5/8″ (1.5cm) from the cutting lines. You can see mine lightly traced in pencil in the photo below.

We’ll need them for some steps later on, and it’s easier than just eyeballing where the seamlines should be.

Line #3: Draw a straight line, at a 90 degree angle to the first line, somewhere near the bottom. I missed taking a photo of this step, but you can see the little line number three in the photo below where I’ve started to cut the pattern apart. (Look for it near the tip of the scissors.)

As you might have guessed, now we’ll cut our side front apart! Cut along Line #1 as shown in the photo above. Cut from the hemline up, all the way to the corner of the line, and follow the line around the bend. Stop at the seamline at the armhole.

Now cut from the armhole inwards, snipping a little cut into the seam allowance. You’re leaving just the tiniest little bit of paper at the seam allowance, to act as a hinge for pivoting the pattern piece. You’ll see in a minute how it all comes together!

Now, cut along Line 2 from the sideseam, inwards. Again we’re leaving just the tiniest little bit of paper uncut, where this line intersects with Line #1.

Next, cut up Line #3, all the way through. (I’ve started to spread out the pattern pieces in the photo below, but don’t worry! We’ll go through all of the steps together.)

Ok. Time to spread out our pattern pieces on these special cutting lines. Again, this is the same concept no matter how much you have to add. Remember how much we have to add? Diana needs 1″, so I’ll spread Line #1 apart by 1″.

But first, I’m going to tape down the left side of the opening. It’s really hard to slash and spread if the pieces keep moving! Add extra paper underneath the opening, and tape the left side to the paper. Take a look at the example below – you can kind of see the clear tape along the left side. Also, there’s no shadow where the piece is taped down.

Now that we have one side of the opening secured, let’s add in the correct amount. Measure the amount to add, at the top part of the opening.

Before you tape it down, measure the opening all the way down and make sure the distance is the same all the way from top to bottom.

Move down the lower seam allowance piece, on the left here, so that the hemline is lined up on both pieces.

Here’s what your piece should look like, so far:

Almost done with this piece! We have added a dart in the sideseam, and we need to get rid of it. (That would look really strange, a princess-seam blouse with a bust dart too!)

Take your imaginary bust-dart-line and extend it into the princess line. Just draw a straight line, using a ruler, as shown below:

Here’s the line with the ruler out of the way:

Now, we’ll cut up this line from both sides. Start at the princess line and cut inwards, stopping where the arrows are pointing.

Next, cut from the sideseam inwards, stopping just before you cut through to the other side, leaving just a tiny bit of paper as a hinge. (Note: I need to cut this piece because I have extra paper taped underneath. If you just filled in paper where you needed it without any extra, you might not need to slash here.)

And now, the dramatic final step! Pivot the bust-dart closed, so it opens up at the princess line. It’s not so dramatic, but it’s still cool watching it all come together. Now we have extra width to cover the bust, and extra cuppage along the princess line – without affecting the shoulders or armhole!

Add a little extra scrap of paper to fill in the bust curve.

And draw in the cutting line, continuing the curve as shown.

Ta-da! A full-busted side front pattern piece!

Ok, we’re very nearly done. Now that we’ve added to Side Front, we need to add to our Front piece as well, so it matches. Our Front piece right now is too short to match our curvy Side Front.

This adjustment is much easier! First, measure the amount we added at the Side Front bustline. Measure along the seam allowance, not the outer edge.

I also measured how far up the adjustment was, above the notch.

Then we go back to the Front piece, and measure up from the notch, the same distance as the Side Front.

Draw a straight line across the pattern piece.

Slash along this line, and add an extra piece of paper underneath. Tape the extra paper to the top edge of the slash.

Now, measure off the distance from the Side Front and tape down the lower edge. Draw in the cutting lines, using a ruler.

Last step! Measure the extra space added at Line #3, on the Side Front piece. We’ll need to add this amount to the Front piece as well.

Add this amount to the Front panel as well. I measured up from the hemline so the additions are in the exact same spot, slashed and added in the right amount. Same as we did in the previous step!

Those are our pieces – we’re done! Phew. That was an intense adjustment! Does everything make sense, for those of you following along with your own adjustment?

I’d highly recommend Fit for Real People, as a fitting resource! See if you can borrow a copy from your library to see if you like it. The photos, illustrations, and real-life examples illustrate a variety of fitting issues. You get to watch the pros work their magic and fit garments on a range of different bodies. That’s where this method comes from!

I also rounded up a bunch of FBA links, for more references!

A Round-up of Related FBA Links:

• Full Bust Alterations (or Adjustments) ~ FBA (From the Sew, Mama, Sew blog)
• Helpful Links for Bust Alterations (From Gertie’s Blog for Better Sewing)

• Guest Post: Lady Grey FBA! (From Gertie’s Blog for Better Sewing)
• Alterations: Full Bust Alteration for Princess Seams (From Stitches and Seams)

FBA-adjusters, what do you think? Is this the method you use? Any other links to add to the list above?

Also, is there anyone who’s muslin-ed or made the blouse that has done a FBA? Or, anyone that didn’t need one, that usually does? Feedback is welcomed on all things FBA-related – leave us a comment below!