Full Bust Adjustment for the Libby Shirt

 Whilst the Libby Shirt is a roomy pattern, you may be used to doing a full bust adjustment (FBA) for many garments. Our patterns are drafted for a B-cup, so if you have a larger bust, you may wish to do an FBA.

To work out if you need to do an FBA, first find the difference between your high bust and full bust. If the difference is 3” or more, we'd recommend making the adjustment. You'll want to choose a size that best corresponds to your high bust measurement for your FBA. If you chose a size that fits your full bust you’ll find it will be too big everywhere else, especially as the shirt is quite boxy. With this FBA method you will end up with a bust dart in the pattern, which you will need to sew up as you would normally.

To figure out how much room you need to add into the front of the shirt for your FBA, work out the difference between your full bust and your high bust. Minus 2” (this is how much is drafted for already for a B-cup) and halve what is left to find out how much you need to add. (We only add half here, as when you cut a pair this will equal the full amount you need to add across the whole shirt).

For example, if you have a 4 inch difference between your high bust and full bust, you'll need to add 1" of room into the pattern: 4”-2"=2. 2"/2=1”.

Making your full bust adjustment

1. Hold your pattern up to yourself/try on your toile and mark your bust apex directly onto it using a felt tip. (Your bust apex is usually where your nipples are!)

2. Transfer your bust apex point to your pattern piece from the toile if you’ve made one.

3. Draw a line from the bust point down to the hemline (line 1), parallel to the grainline.

4. Draw a diagonal line from the bust point to the upper notch on the armhole (line 2).

5. Draw a third line from the bust point to the first notch on the side seam (line 3).

6. Cut through lines 1 and 2, but on line 2 stop when you reach the seam allowance on the armhole.

7. Cut through line 3, but again leave a small amount uncut at the bust apex.

8. Tape your pattern down onto a piece of pattern paper, just along the centre front and line 1 to start with. Draw a line parallel to line 1, at the distance you need to increase by to the left hand side of this line.

9. Move the pattern until it sits exactly on this line, as shown above. Tape this section of the pattern in place.

10. Line 3 will have opened up to accommodate the width you’ve added, so tape it in place where it has opened up. This will look like a dart, and you will need to sew it up like one when making your shirt.

11. To level the hem on your pattern, cut all the way along the lengthen/shorten line on just the right hand side part of the pattern. Shift this new piece down until it lines up with the hem again. This is shown above with the green lines.

12. You will then need to true up the centre front again, by re-connecting the two lines. You will also need to do this with the hem.

13. Trim down the excess paper around the pattern, except at the side seam as you still need this.

14. You then need to redraw the dart. Double check your bust apex is in the right place by holding your pattern up against you. Re-draw it if it seems slightly off. Create two dart legs connecting the bust apex with the cut openings of line 3 on the side seam.

15. As you’ve used your true bust apex to draw in this new dart, you’ll want to move it slightly on the pattern to avoid any pointiness once the shirt is made up. You’ll want to move the dart tip slightly away from the point you’ve just drawn, towards the side seam. We recommend between 2.5cm and 3.5cm from the original point. The bigger your bust, the further away you will need to make the new dart apex.

16. Draw in the new dart legs as shown above.

17. Fold the dart closed, bringing the lower leg up to sit on top of the upper leg. Tape or pin down. Cut along the side seam of the pattern piece, at the same time removing all of the excess paper.

18. Remove the pin or tape and open up the dart again. It can be helpful to cut in new notches for the dart leg ends at the side seam at this point so you remember to snip them when cutting out your fabric. 

Working with your new pattern

Your pattern should now look something like this.

The tailor's tack marks the apex of the dart.

As per the Libby Shirt instructions, stay stitch the neckline edges. Then sew the darts as normal.

1. Mark the darts onto your fabric using tailor's tacks and a fabric marker. The dart apex should meet the two notches you snipped in the side seam.

2. Pin the darts closed, making sure your pins go through the fabric marker lines on both sides of the dart legs.

3. Starting at the side seam, carefully sew towards the dart apex, following the lines you've drawn with the fabric marker. When you reach the dart apex sew straight off the fabric without back stitching. Leave long thread tails and, with the knot as close as it will go to the fabric, tie the threads together to prevent your stitching from unravelling.

4. Press the dart towards the hem, first from the wrong side and then again from the right side.

And voila! That's your full bust adjustment made and sewn! Continue with your Libby Shirt as detailed in the instructions, if you need help with the collar, we have a blog post to take you through every step here.

Don't forget to share your version once it's finished using the hashtag #SOIlibbyshirt hashtag on Instagram, we can't wait to see!

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