Patterning Basics - Princess Seam Manipulations on a Bodice Block

With the past two journal entries, I’ve walked you through how to draft your own bodice block or sloper. Now, I am going to show you one application for those blocks. You can use the slopers as pattern pieces as they are now - that’s why they’re there and why we drafted them. But sometimes, the darts are in the wrong place, or you’re trying some really complicated thing, or darts aren’t the look you’re going for. Today, I’ll be showing you how to turn your dart-blocks into a princess seam style.

A princess seam is a curved seam that fits to the contours of the body without the use of darts. We see it in historical examples with cuirass bodices from the 1880s, those lovely wool suits and coats from the post-World War Two era, and some formal modern styles. I love the look of a princess seam - there’s something so elegant about it. As an example, the Julie Suit that I’ve talked about previously on this blog has princess seams in the jacket. You can just buy a pattern that has done the math for you (I certainly did that with Julie Suit), but like I’ve discussed previously, there’s something so satisfying knowing you were the one to make something from the very start to the very finish.

I also wanted to challenge myself with this year’s birthday dress. In the past, I’ve always Frankenstein-ed multiple patterns together. It’s a technique that works, but it can be a lot of brain power. Often, I had to draft pieces to supplement my design, or re-draft the patterns to get everything to play nicely together. No more, I said to myself this year, I’ll do it all myself. It also worked out with what I had planned for the blog in June and July - easy enough to get two things done with one project.

Step One: Having Your Blocks and Creating Style Lines

You’ve got your blocks all drafted and ready to go! (If you don’t, go check out the posts from June to get the instructions.) I recommend tracing your blocks onto new paper, so that you’re not destroying all your hard work when we cut into the pattern to manipulate it. Once that’s done we can start on the style lines.

There are a couple different kinds of princess seams. For my birthday dress, I wanted something with a more dramatic curve and shape. I’ll be showing that alteration - it’s technically called an “armhole princess style line”. The process is sort of in the name, but it’s a little less complicated in practice than it is in name.

On your front block, find the midpoint of the armhole. From there, draw a curved line down to the point of your dart. That’s your front style line. We’ll refine that shape in the next step, but let’s mark our style line on the back first.

There’s an extra step to the back. That pesky shoulder dart needs to be closed up before we can do anything else. On your paper pattern, draw a line from the point of your dart over to your armhole. Cut along that line until there’s just a tiny bit of paper still connecting the upper armhole to the rest of your block. Swivel that piece until your shoulder dart is closed. Tape it shut. If you need to, you can trim the armhole so that it’s a smooth curve again. That shoulder dart is important to get things to fit along the curve of your shoulder, and in closing it in this manner, we’ve transferred the dart fullness to the armhole. Find that mid-armhole point again and draw curved line from there to the tip of your back dart. There’s your back style line.

Step Two: Refining Your Curves

Cut both blocks along your style lines. There should be four total pattern pieces now, and maybe they look a little strange. We’ll fix that now. Your front and back pieces are as close to finished as they’ll get. I added an extra .25” inch of ease to my side-back piece, just to have a little bit of wiggle-room if I needed it. My side-front piece looked weird when I separated it. That’s because that side-front piece still needs that dart allowance added back to it. It needs .25” ease around the top, and the angular line left from the dart needs to be refined into a smooth curve. In this step, it’s important to leave that bottom line alone. That’s your waist measurement and doesn’t need altered. It’s the area around the bust and armhole that needs the alteration.

Step Three: Trueing

Trueing is the process of making sure all of your pattern pieces match up with each other in smooth lines. In this case, we need to true the armholes. Don’t take away anything here - we’re going to add. Where the armholes don’t meet, you’ll draw from the taller piece and add to the shorter piece to make everything even.

Now that your lines are trued, blended, and evened, you have your finished pattern pieces!

Step Four: Further Alterations

You should always make a mock-up to make sure everything fits properly. I had to take out half an inch from my front pieces and a quarter inch from my side seam. It is what it is - I’d rather remove some excess from my patterns than do the mental gymnastics to add things. From there, you can add further style lines. I altered the neckline to be lower and more of a sweetheart neckline, and I evened out the back and the armhole.

Birthday Dress Tutorial: Princess Seam Bodice with a Tiered Gathered Skirt

For my birthday dress, I used my princess seam bodice block that I altered like the Step Four instructions and added straps that tied. These straps were each fourteen inches long and I cut eight of them. The tiered skirt took more math than I would like to admit, so I’ll give you the final solution here. The first tier was 10” tall and the entire width of my fabric (53”). I added pockets here. They were super simple, just two 6.5”x6.5” squares. I added an inch of seam allowance to the top edge and topstitched this down. I then top stitched the pocket to the sides of the skirt tier. The second tier was two of those 10”x53” strips. The third tier was three of those strips, but if I had to do it again I would use four 10”x53” pieces. I think that would have made gathering it much easier and all my seams would have aligned perfectly. Three pieces worked, but it was something of a struggle. Using four pieces in the bottom tier will also give you more fullness overall.

And there it is! I loved this year’s birthday dress; it was fun and summery and had a great volume to the skirt. This design is also super easy to customize - you could add tiers or subtract them, add stripes or trim, put a ruffle at the hem… I’ll actually be using this pattern to make a top with the bodice and just the first tier of the skirt. The whole project used about four yards, but I have some significant scraps left over. The fabric is from Firecracker Fabrics, and I’ve linked them below!

If you make this dress or do any project with this pattern alteration, tag me on the social medias! I would love to see your projects! If you’re not a sewing type of person, and you’re just along for the ride, I’m happy you’re here too. Stay tuned for upcoming posts and projects! The next blog post will be pattern related as well, but it might be a little more exciting for you…

Until next time, dear reader.

Yours sincerely,

Madeline