How to add a bust dart to a sewing pattern
Today I'm going to show a few methods of adding bust shaping to a sewing pattern.
Hello my mathy friends! In today’s post, I’m sharing a few ways to add bust shaping to the Shirred Babydoll Dress. (Click here to catch up on all the posts in this series.) This pattern is drafted using measurements from above the bust and then has gathers to create ease through the torso. This works fine for some people but if you have larger breasts, you may want to add more shaping to the front bodice. (As drafted, the pattern has the same pattern piece for the front and the back but we all know that our bodies are not the same front and back.)
In my previous post, I shared how to estimate the Finished Bust/Hip Circumference so that you can determine how much ease there is before fully drafting the pattern. That’s a great first step. But even with enough ease in the circumference, if you have larger breasts, you may see pulling around the breast or the hem may be higher at the center front. By adding more shaping, the style lines of the dress will be less distorted.
I found three different ways to add bust shaping: a quickie FBA, adding a dart, and an FBA without a dart. I’ll show you how to do each adjustment and then compare the three with the original pattern.
The amount of adjustment you need to make depends on your body and may take some trial and error to figure out. I wish there was a foolproof, 100% clear cut way to do this but from my research and talking with other people, there’s not.
In general, I recommend taking the difference between full bust and upper bust. Then, subtract 2” and divide by 2. That’s the “X” adjustment to make. For example, if you have Full Bust of 50” and Upper Bust of 44”, the difference is 6” (aka a sewing F cup). Subtract 2, and we get 4”. (This subtraction of 2 is a little arbitrary and based on how much ease there is.) Then divide by 2 (because we’re working with half the pattern) and we get a 2” adjustment.
How to do a Quickie Full Bust Adjustment
This method is really the same adjustment that we made to the sleeve to even out the sleeve hem. This adjustment is best for those on the smaller side of large, like a C or D cup, because it only adjusts the length and not the width or shaping. With larger busts, we often see the hem lift up in the center front so this adjustment counteracts that.
Step 1: At the bottom of the center front, add “X” adjustment to the length. Using a gentle curve, connect this point to the left bottom corner.
Step 2: Redraw the hem allowance.
How to Add a Side Bust Dart to a Pattern
This method is similar to a classic Full Bust Adjustment and will add shaping and width to the breast area and length to the front bodice. Because the dart area will be pinched out when sewn, the side seam should remain the same as the back bodice.
I would recommend this adjustment to anyone with a DD/E cup or larger.
Step 1: Find and mark the bust apex. (If you haven’t made a muslin, you can hold the paper pattern up to your body and mark the center of the breast.) Draw lines from the bust apex to the armpit, to the side seam and straight down to the hem. Draw a horizontal line from the center to the vertical line.
Step 2: Cut along the lines, leaving two hinges, one at the armpit and one connecting the two bottom left segments. The hinge points are marked with pink/red dots in the illustration.
Step 3: Move the hinged pieces to the left and down, keeping the bottom left piece parallel to the cut line, until you have a gap equal to your desired adjustment “X”. Move the bottom right piece down to align with the bottom left segment.
Step 4: Redraw the outline of the pattern piece. You can give a gentle curve to the armpit but double check that the length of the seam line is the same as before. Draw the dart with the end of the dart at least 1/2” away from the apex.
How to do a Full Bust Adjustment without a Dart
If you want an FBA but don’t want a dart, for whatever reason, this method is for you. This adjustment starts off just like adding a dart, but keeps going to then remove the dart. It’s kind of a hybrid of the first two methods, adding both width and length to the front pattern piece.
Step 1: Complete steps 1 through 3 from the How to Add A Dart instructions above. Starting at the inner point in the triangle segment (marked with a pink circle), pivot the lower left segment clockwise to close the dart.
Step 2: Starting at the side seam/upper left corner (marked with a pink circle), pivot the lower left segment so that the side seam is parallel to the center front seam.
Step 3: Redraw the outline of the pattern piece. You can give a gentle curve to the armpit but double check that the length of the seam line is the same as before. Draw a new curved hem that connects the side seam to the lower right panel.
Finally, let’s take a look at how these different adjustments changed the pattern piece. In the graphic above, I’ve shown the original pattern in the top left and the three adjusted pieces to the right. Below, I layered the pattern pieces with the original on top with a dark outline. The FBA with and without a dart both add width and length to the front pattern piece. In my experience, a dart creates the best shaping for the bust because more than just adding ease, it creates a shape to fit the curve of the breast. The method you choose is up to you.
I hope that you enjoyed this post. In my sewing experience, I have found that bust adjustments make a huge difference in fit. Total game changer. Next up, I’ll be sharing my own version (or versions!) of this dress. If you enjoyed this newsletter, you can support by sharing or clicking the heart at the top or bottom of the post.
Happy mathing!
Beth
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