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  • Blocking: "Encouraging" Your Blocks into Shape

Blocking: "Encouraging" Your Blocks into Shape

Although the importance of accurate seam allowances is drilled into every quilter, most of us end up with blocks that are not quite the right size at times. Knitters are masters at "blocking" their pieces into shape, and quilters can add this skill to their arsenal, too. We'll show you how to do this using sample blocks from Jinny’s Starstruck BOM quilt.

You will need:

  • your not-quite-perfect block
  • a pressing surface into which you can pin firmly
  • a permanent or erasable marking pen
  • ruler (a large square is great)
  • T-pins (they are large, sturdy and can hold up to heavy steam)
  • a steam iron

Most of us have a portable pressing surface with gridlines. We like to cover ours with muslin or another light-colored cotton fabric for two reasons: the gridlines probably don’t match our desired block size, and (if you are like the Studio staff) the pressing surface is likely to be a little grungy!


Stretch the fabric over the pressing surface and pin it in place. Mark the desired block size on the cloth. Here we've used a heat-erasable pen which makes it easy to re-use the cloth for different-sized blocks.  If you will be blocking a large number of same-size blocks, you might want to choose a marker that won’t disappear with heat. In this instance, the block needs to be 12-1/16".

Start by using T-pins to pin each corner of the block and the center of each side, stretching the corners and edges to meet your marked block outline.

It is a good idea to be sure to pin within the seam allowance as the T-pins leave a fair-sized hole. Pin the top and bottom of the block even with the lines, then the sides.

Once everything is pinned, press the block from the center out to the edges, using steam, steam, steam! Let it cool completely before removing the pins.

You might also try spraying your block with a sizing agent after pinning but before steaming. That can help your block hold its shape.

There is a limit to how much you can stretch a block, but this technique can give you blocks that are much closer to the desired size -- which will make assembling your quilt much easier. Blocking with steam can also be used to shrink up a block a little bit.

As always, we recommend you test this process on an extra block before trying it on one destined to be used in your next quilting masterpiece!