Shape Matters: Why the ultra-basic corset draft doesn’t work for every body.

I made my first Elizabethan corset back in the dark ages of internet time, when it was still pretty common to ask Real Live Humans(tm) how to do things.  I got instructions that were relatively simple – a bust, a waist, divide by two, draw some lines, and presto-change-o, a corset pattern.  It’s the method that had always worked for the lady who gave me the info.  For me, it was a spectacular failure – too tight, too high in back, and completely uncomfortable to wear.  I blamed it on my generally costume-clue-impaired state.  But was there something else going on, that could result in two people having completely different luck with the same pattern draft?

The answer, in case the title wasn’t a dead giveaway, is that she and I had different body shapes to contend with.  The female torso comes in a myriad of different forms and sizes, but they all fall into one of three categories: bust and waist are relatively equal, bust is significantly larger than waist, or bust is significantly smaller than waist.  Let’s look at simplified versions of three classic body types: the curvy Hourglass, the relatively straight Column, or the tummy-heavy Barrel.

It’s starting to look a lot like Geometry class in here again, isn’t it?  Each of these paper models is a simplified version of a body types.  (They’re really rather oversimplified, actually, but I’m not very good at making paper models.  They’ll do for the purposes of this demo.)  I’ve marked the Bust, Waist, High Hip and Full Hip levels, as well as the Center Front and Side lines.  I’ve kept them as consistent as possible.  The Column (center) is the most basic shape.  This one corresponds to a woman who is roughly, say, 40-40-40.  The Hourglass (left) is roughly equivalent to a real woman at 42-35-42.  The Barrel (right) is the opposite, coming in at 35-42-35.  That’s only a 7″ difference between bust and waist in either case – not much on a real human.

The standard issue, super-basic Elizabethan bodice draft goes something like this: pick a starting point: center front for back lacing, center back for front lacing.  Make a line to represent this.  Mark out half the waist measurement, at right angles to the starting line.  Measure up from the waist line the distance between your bust and waist.   Draw a line at this level.  Mark, starting from the original starting line, half of the bust measurement on the bust level line.  Add a curve for the armscye at the half-way point on the bust line.  Add some straps, maybe, and your seam allowances, and you’re done.  Sound familiar?

The Ultra-basic draft does all of it’s shaping at the closing edge.  I’ve drawn up the pattern for the three different body shapes in question.  (I’ve never noticed how much they look like frog faces before….)  You can see the effect of the different measurements: the Column gets a straight closing edge, while the Hourglass and Barrel will end up with edges cut on a pronounced bias.  That’s already a problem, but things are about to get a lot worse for the curvy girls….

It’s important to note that we started this draft at the center front line.  That means that here, in the front, the draft is relatively ok on all three body types.  It’s best on the Column, but it at least appears to lie correctly (if not smoothly) on the other two.

When we look at things from a different angle, the problem becomes more clear.  The ultra-basic Elizabethan draft works perfectly on a figure that’s relatively straight.  On the Column, the bust and waist level of the bodice draft follow the bust and waist lines marked on the model.  On the Hourglass and the Barrel, however, things don’t go so well.  The lines of the draft angle away from the lines of the model.  By the time we get to the closing edge, the situation is dire….

All three of these drafts were made to exactly the measurements of the paper models.  Only the Column closes fully at the center back.  The Hourglass has a bodice draft that rises way up from her waist in back.  Because the bodice is diverging from the actual bust and waist lines of the figure, it’s taking a longer path (around and up) than the path straight around the body.  It no longer closes, and the armscye has moved into an awkward place.  (The straps, if they were real, would now ride above the shoulder and fall down constantly.)  The Barrel has similar problems, but in the opposite direction.  Her bodice goes below the waist in back, her armscyes have moved downward, and her straps will now be far too short to accommodate her arms.  On real bodies, which can be squished, it’s possible to close the bodice, but it’s going to feel much tighter than expected and the fit will be uncomfortable.

So what happened?  The answer lies in the difference between cylindrical and conic solids.  The Column is a cylander.  When we flatten it, it looks like this:

All of the critical lines of the body (bust, waist, hip, center front, side, etc) are straight.  The horizontal and vertical lines meet at right angles, in a neat grid.  Geometrically, a cylander is nothing more than a rectangle wrapped around a circular base.  It’s very simple to pattern and make, which is probably why it’s such a popular shape for soup cans.  (Even though it makes them all squirrel-y on shelves….)

Now let’s look at the situation with the Hourglass and the Barrel, whose forms are made up of conic sections:

Here’s the half assembled Hourglass shape.  To make the inward angle all around that represents the waist, I have to use two pieces of paper, each cut on a slight curve.  A conic solid, like this, isn’t a simple rectangle-around-circle idea.  Technically, it’s a two circles of different sizes (the ends) with a surface between them.  If that surface were a normal rectangle, it would only fit one of the circular ends.  To work, the surface has to have one side longer than the other.  Just like our simple bodice draft, however, it’s not enough to just add the extra in at the end of the line – that would make a a sharp point when the angled edges are joined.  The extra size needs to be spread out evenly over the length of the line.  You can’t do that with to straight, unbroken lines.  You need curves.

The problem with curves, however, comes when you try to draw a level line parallel to a curved edge.  That line must also curve, as we see above with the bust-line marked on the flattened piece. (Technically, the fact that it’s curved means that it’s no longer a line, as lines are, by strict mathematical definition, straight.  For the sake of readability, I’m going to continue calling them lines instead of the more correct “arcs”.)   To complicate things further, any line that crosses several of these curved lines at apparent right angles is now set at an angle, as you can see when you look at the side and center front lines.  They appear to be radiating out from some distant point.  The whole thing’s gone completely skew, hasn’t it?  It’s almost like looking at a the parallels and meridians marked on a globe…

That’s because we’ve moved out of the neat, orderly world of the geometry that operates on the flat  Cartesian Plane, and into the very odd, not-at-all-meant-to-map-flat-things world of the Polar Coordinate System.  (We’re not going too deeply into that.  Frankly, I never got on well with radians.  The sight of all those thetas still makes me twitch a little.)  You do need to know, however, that things drawn on a Cartesian grid (all the lines are straight and meet at right angles or not at all) will not overlay a polar grid (parallel curved lines crossed by lines that radiate from a central location), even though they are technically the drafted to the same size.

You need a curve to fit a curve.  Technically, you need the same curve, not one that’s more or less curvy.  This is crucial when drafting patterns.  The problem, unfortunately, is that rulers tend to be, well, straight.  So what’s a girl to do?  The corset pattern explained on the Elizabethan Costuming Homepage mimics a curve by instructing that points be dropped below the marked lines at several points during the draft.  I prefer to use shorter lines in my drafting.  Mathematically speaking, many short lines can be used to approximate a curved line, yadda yadda yadda, Bezier Curves and Calculus, oh my.  Remember, back in the day, when it was really popular to put little nails around a wood frame and and string it up so that it looked like there were curves or circles in the middle where the string wasn’t?  Ah, String Art, how I miss thee….  Amazingly, we were all crafting our way through some pretty heavy Calculus.  (And if my first pre-calc teacher had busted out the nails and the string, I might have passed the class on the first go.)

So, here’s another take on creating a pattern on a straight grid, which will overlay a cone smoothly….  This is the basic approach I use any time I have to draft a corset (for any era, actually), and it relies on the fact that it’s easier to draw triangles than curves.

You start with your largest measurement.  It doesn’t matter if that’s the bust or the waist.  Draw out one half of your largest measurement.  Mark the half and quarter points of this line.  From the half point, drop a line at right angles measuring the length of your bust to waist measurement.  At the bottom of that line, again at right angles, draw out the length of half your longest measurement again.  Mark the quarters.

Next, we need to remove some length from the line that should be shorter.  I’m working with an Hourglass shape, so I need to take length out of the waist line.  (If you’re working with a Barrel shape, you’re going to do the same things, but you’re going to do them upside-down.)  I’ll be taking out at three points: the half point and the two quarter points.  To figure out how much to take out, I subtract half the waist from half the bust, the divide that evenly over my three chosen points.  In this case, half the bust is 4 3/16″, and half the waist is 3 1/2″.  The difference is 11/16″, which is close enough to 3/4″ for me.  Divided evenly over three points, that’s 1/4″ at each point.

Center the difference measurement on each of the three points.  In this example, I’m marking 1/8″ to each side of the half and quarter points.  (Those are the blue ticks on the lower line.)

From each of the blue ticks, draw a line up to the corresponding half or quarter mark on the bust line.  The long wedges represent area that needs to be removed from the original rectangle we drew to make it into two smooth curves.  Essentially, removing these wedges allows us to shift from that flat Cartesian grid into a body-friendly polar grid.  (There’s math for doing this, but it’s messy and it’s mostly in Greek letters.  My sister understands it.  I’m really more of a visual learner…)  How?  Well, the whole thing with polar coordinates is that they revolve around a central axis.  All horizontal lines are composed of points of a defined distance from that central point, and all vertical lines radiate from it.  By removing little wedges, evenly spaced along the lines, we’re creating a set of lines that point to that magical central point.  The bust and waist lines are being bent into curves in the process, but they remain a constant distance from each other (and our mythical central point).  Thus, we’ve accomplished Heavy Math(tm) without brain sprain.

Still don’t believe it?  Watch….

So that’s the absolute, theoretical basics of how to draft a corset pattern: draft everything to your widest point, then take out all the extra.  It’s really not unlike the zen thing about carving an elephant – start with a block of stone, and remove everything that is not an elephant.  I mean, sure, ok, well that’s really helpful there, Little Miss Zen Master, but is there any way we could get just a touch more specific?  And, really, no one’s torso is a perfect cone.  Didja think about that one?

Oh….  So you want specific applications of the theory?  Stay tuned….  We’ll start with a better basic Elizabethan corset/bodice pattern draft, and then, who knows – maybe we’ll get saucy and hit the Victorian era.