Top Five Tips: making Half Square Triangles

Tip One

Usually, half square triangles (HSTs) are made from fabric squares. This is because squares are easier to work with than triangles. Sewing diagonally across the grain of fabric is more difficult because you are sewing on the bias, and this means it’s easier for the fabric to distort. As half square triangles have a diagonal seam, you have to deal with fabric bias at some point but sewing across a square gives your stitches some extra support. There are lots of different methods for making half square triangles and all of them have their pros and cons. It’s important to choose the best methods for you based on your priorities. My favourite method is ‘two at a time’ which involves sewing two parallel diagonal seams across two right-side together fabric squares and then cutting them in half between the sewn lines. From two fabric squares you create two half square triangle units. I like this method because there’s no fabric waste and I find it makes very accurate half square triangles.

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Tip Two

No matter which method you use to make half square triangles, I would highly recommend choosing one that creates them slightly bigger than the size you need for your patchwork project. This means that once you have sewn and pressed the HST unit you’ll need to trim a little from all four edges. Yes, this does mean it takes a little long but it also means it’s much easier to get an accurate and perfectly square half square triangle.

Bonus tip: use a ruler with a 45° line to trim your HSTs and make sure the 45° line is always on the diagonal seam.

Tip Three

Plan ahead. Before you start pressing your HSTs, think about how they are being placed in your overall patchwork design. You might find it better to press them in a few different ways. Things to look out for include:

• dark and light fabric – try to press seams away from the light fabric, or press the seams open, so the dark fabric seam allowance doesn’t show through
• seam nesting – if the diagonal seams of two HSTs are meeting, can you press them in different directions so the seams can nest together meaning you’ll have less bulk and it will be easier to keep the seam matching nice and accurate
• watch out for bulk – lots of HST seams meeting in one place can become very bulky so if your design needs this to happen, plan to press some (or all) of your seams open to reduce the bulk.

Tip Five

When you break it down there are lots of steps to making half square triangles; cutting, marking, sewing, pressing, trimming, and piecing into a project. It’s really important to remember that all of these steps are equally important. Don’t rush over any of them to get onto the next one.