Math is your friend

Author: fraise

Wednesday 13 June 2012, in Crafts, Journal

You may have heard of the intersection between theoretical mathematics, knitting and crocheting, but as any seamstress or tailor could tell you, there’s also quite a bit of math in clothesmaking. Not just measurements, but pattern layout. This is a simple example, but it’s a good illustration of how a little familiarity with math can make creation easier.

A few weeks ago, I fell in love with this fabric, and hoped to make a border print dress with it – a flower border on top (the bodice) and another on the bottom hem.

When I received the fabric, I noticed that the center “stripe” of darker flowers was twice as wide as the selvedge stripes, with white space between the selvedge stripes and the center one. It wouldn’t work for a dress that had a natural waist seam, but just might for a dress with a higher waist. I looked to math to help out.

The fabric was, essentially, divided into sixths: 1/6 selvedge pattern, 1/6 white area, 2/6 (1/3) center pattern, 1/6 white area, and the opposite 1/6 selvedge pattern. Its full width was 110cm. I had a dress pattern I thought might work: Butterick B5369. It met the following requirements, based on the fabric: it had a gored skirt (in sections), meaning that no one skirt piece had a particularly large curve to it. With too pronounced a curve, the skirt would have delved into white space and turned out with an unbalanced appearance. The pattern also had an empire (high) waist, and measured 90cm from bodice top to bottom hem, meaning, on a practical level, that the dress was essentially… divided into fifths related to my fabric! One-sixth of 110cm is 18.33cm, and 110 – 18 = 92cm. As for the dress’ proportions, it would mean 1/5 bodice, 1/5 top waist, 1/5 lower waist, and 2/5 bottom skirt. I could do 1/5 + 1/5 dark stripe for the bodice and top waist, to balance the proportions with the 2/5 stripe on the bottom.

In this case, in sewing, all you have to do is “subtract”, i.e. not use, one of the sixths, which has the bonus of making that extra sixth available for use elsewhere. You do have to be careful to cut everything properly, not accidentally cutting a 1/5 part in a 2/5 section, for instance. That all probably sounds confusing to non-sewists, so I used my stellar Gimp skills to create this über-high-tech illustration of pattern layout. In reality, I cut the skirt pieces much closer together, so as not to waste fabric.:

The long pieces are the waist + skirt gores, while the small bits are bodice pieces (not all of them). You can see a straight line on each bodice piece: they’re meant to be cut on a fold, as was the front center skirt gore, while all other pieces are cut in pairs. (There are exceptions depending on patterns, but this dress happened to have a 7-gore skirt and a 4-piece bodice, though I made the back bodice as a single piece, taking it down to a 3-piece bodice, because I wanted to put a zipper in the side rather than in the center back. Everyone still following? Heh. The bodice changes are tangential to the math bits.)

You may have noticed another interesting side of math’s friendliness: the skirt gore pieces line up very nicely on the selvedge! Indeed, it was a piece of cake to match the stripes, because all I had to do was place the skirt pattern piece’s top (bodice seam line) edges along the selvedge, and make sure they were straight with the cross-grain (skirt length). It also helped that the fabric is not an exact “stripe”, so that the piecing ended up being a nice echo to the motif’s scattered blossoms. The finished proportions ended up like so – I put in a darker line where the bodice seam attaches a sixth to another sixth:

And, naturally, the finished dress! Five cheers for math!

Flower dress - B5639

6 responses to “Math is your friend”

  1. Ellen Says:

    I absolutely LOVE your finished dress!! I have begun quilting, and mathematics plays a huge role in piecing, cutting and sewing.

  2. fraise Says:

    Yes, quilting blocks could be a mathematics and/or geometry class in and of themselves! It’s so much easier to grasp spatial concepts as related to mathematics when you hold a representation of them in your hands.

  3. emilyadi Says:

    My mom is an avid sock knitter and she agrees. She is always coming away from conventions and such remarking how smart the people are who attend. Mathematicians, physicians, and engineers are very common among sock knitters.

  4. Mar Says:

    I’ll be honest. When I saw the fabric at the top of the page, I didn’t like it. But once I saw the finished dress… WOW! Loved!! So, now I wonder if I would have any talent at all to look at a fabric and imagine a finished piece. I don’t think so… Congratulations for your skills and the gorgeous dress!

  5. Mitr Friend Says:

    Wow… This is so pretty and clever!!! Loving it…
    And that pattern by itself is nice and the way you’ve stitched it is great…
    May be you have time to drop by my blog.
    Fashion Panache

  6. Dennis Gentry Says:


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