Tuesday, August 21, 2012

Block pattern (sloper) drafting

A number of vintage sewing books include instructions on block (or sloper ) pattern drafting. Instructions are given on taking measurements from your body to draft a basic bodice, sleeve, skirt and occasionally trousers. You make up a prototype in calico (in Australia, NZ and the UK) or muslin (in the US). This prototype is called a “toile”. Having tried on the toile, you mark any changes necessary and modify the drafted pattern accordingly.

The patterns may then be modified to create a variety of styles.This is done by folding parts of the pattern, and cutting and spreading other parts of the pattern, taping your changes in place and then tracing the result to create a new pattern.

Here is how a draft of the front bodice from one of these books might begin (if you were messing around with Adobe Illustrator rather than a pencil and tracing paper):

draft bodice block

The red lines are construction lines and the green the (nearly) final shape. After that, darts, pleats and shaping are added until you have drafted something that looks much like a commercial pattern.

My reviews of vintage books include giving their block patterns a test run by drafting a pattern and making up a garment. I make up commercial patterns from the same periods as well. WARNING: I won’t be creating authentic period garments. I’m aiming to make things I can wear comfortably in the 21st century in Southeast Queensland. All done on a pretty tight fabric budget.

Why am I bothering with vintage block pattern drafting when you can still get vintage commercial patterns?  I think it’s fun and I feel like I’m experiencing a little piece of history as I do it. It's also not always possible to purchase the vintage pattern I want. Maybe I just can't buy it, or it comes with such a hefty price tag that I'll be left cutting up the cat's cuddly rug for fabric.

Skills needed for Block Pattern Drafting:

  • Basic arithmetic and geometry.
  • A steady hand.
  • Some prior sewing experience.

Equipment needed for drafting by hand:

  • Pencil, eraser, scissors
  • Tape measure, set square, long ruler (probably at least one of these with both metric and imperial measurements)
  • A big roll of tracing paper ( I visited a local drafting supply shop and got a nice big roll that’s tough and feels a little like plastic)
  • Sticky tape (preferably the quality stuff that you can write on and peels off nicely when you need to move it).
  • French curves, or a flexicurve would be nice too, depending on how good you are at free-handing necklines and armhole curves.


If you have limited space, want to share your patterns, and have Adobe Illustrator and Photoshop, then check out the amazing tutorials offered by fashion designer Ralph Pink. While you’re there check out his other  tutorials too. Wow.

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