Pattern Drafting

Slopers: a few remarks

A "sloper" is also called a "block pattern" and, probably, other names in other places.*

No illustrations here -- I'm making this file HTML just because it forms a series with two other files that do require illustrations. (If there aren't two other "pattern drafting" files in the table of contents, I haven't finished writing "drafting a dome" yet.)

This is a post I wrote for a mailing list, and didn't get around to posting before the discussion had moved on. I've lost the attribution for the quote at the beginning.


My understanding is that a sloper is a skin-tight form-fitting garment that lets you know you have basic measurements correct. I've never heard of a raglan sloper, a set-in sleeve sloper, a drop shoulder sloper, a kimono sloper. Aren't these test garments called wearable muslins (not necessarily made out of muslin), not slopers?

It has been my understanding that a sloper cannot be used directly to make a garment -- first you have to shorten the darts and add seam allowances.

A sloper is a pattern for making patterns -- and you don't have to start any particular place. The skin-tight sloper with set-in sleeves can go in the most directions, but if all the patterns you intend to make have raglan sleeves, you might draft a raglan sloper to start with.

Indeed, when you use a sloper to design a garment, the first step is to make another sloper, which is then made into a pattern. Sometimes people copy the sloper, whack up the copy, and tape it back together to make the new sloper. More often, they draw around it on pattern paper, sliding and rotating as required to get the effect of having whacked it up and taped it back together, then add seam allowances to the tracing.

I nearly always modify patterns I already have, rather than drafting new ones -- or make a sort of virtual sloper by marking the points where sloper darts would have ended, and rotating around those points instead of the ends of the darts on the pattern. (This is a lot easier if you start out by whacking up cardboard slopers, then start taking shortcuts.)

An example of modifying a working pattern: my latest design was a slip for my long winter dresses: essentially an ankle-length T-shirt. (If it's too warm for sleeves in a slip, it's too warm for a slip.)

I had a length of black interlock, a tested pattern for an interlock T-shirt, and a tested pattern for a jersey slip. Lengthwise, jersey and interlock have the same stretch. So I put the slip pattern on the interlock and drew around it with chalk. Then I pinned the T-shirt pattern to the interlock, matching the shoulder seams and the centers to the chalk outline. I used a ruler to draw chalk lines blending the side-seam cutting lines of the slip into the T- shirt. The slip was for full skirts, so I didn't deduct from the hem for the extra give of the interlock, and I widened the T-shirt tail, blending the cutting lines at the waist.

My current project began when I realized that I wear short skirts more often, my short slip was ugly to begin with, and it's now dangerously shabby. I put the raggedy old slip over the long slip on the same suit hanger -- a dress form would have been better, of course, but I don't have house-room for one -- and measured the difference between the hems.

Then I repeated the above pattern-drafting, but on paper, then measured up from the hem in several places to draw the new cutting line. I didn't like the shape of the hem in back, so I marked the center back a tad lower, then cut out the front and walked it down the back to make sure the side seams were the same length, and marked a new curve with my 45-degree triangle. (i.e., mark lines at right angles to side seam and center back, draw smooth curve connecting.)

And now I'd better stop typing and start sewing, because I was kinder hoping to wear that slip tomorrow.


* Needlework skills have traditionally been passed down vertically, from mother to child and master to apprentice, not horizontally in schools and books, so there has never been any need for standard terms that could be understood outside the family. What with the printing press, popular magazines, and the internet, this is changing, but most concepts still have multiple terms.

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Postscript, 22 July 2011

While reading a mailing list for people who want to design their own sewing patterns, I came across this admirable plan:  She plans first to make a skin-tight sloper and use it to design a dress dummy, then add wearing ease to the dress-dummy sloper to make a sloper for making garment patterns.

One might add to this, as time goes on, a sloper for designing princess-seam patterns, a sloper for designing blouses and dresses with no waistline seam, a sloper for sleeveless garments, . . .

A lower-torso sloper can be used for designing both skirts and pants, one will be wanting at least one pants sloper . . .

Just watching these energetic young folks on the mailing list makes me tired.  I'm so glad that I already have a pattern for every garment I wear!

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