The secrets to accurate Half Square Triangles

When posting on social media, one never knows what kind of reactions the post will get. Case in point, a few weeks ago I posted a photo of my construction process for multiple half-square triangles (HSTs) using single strips of fabric. That post produced many questions on the technique I used. Coincidentally, at the same time, I was asked to write this week’s post and what topic I would choose to write about. Well, without missing a beat, I replied that I’d like to write about the various techniques to use when making HSTs.

To make this week’s quilt, I’ll use some of my favorite Clover notion and tools.

Clover quilting notions and tools

Here’s a look at the quilt I’ll be working on this week. It measures 48” x 60” – the perfect size for my neighbor’s newborn son.

This week’s Marvel Avengers Kids in Action quilt project measures 48” x 60” when complete.

The accent fabric I selected is called Marvel Avengers Kids in Action, available at your local quilt store. I matched this accent fabric with solid colors I already had in my stash.

Here are the fabric requirements for this week’s quilt:

  • ¾ yard [0.7m] Marvel Avengers Kids in Action accent fabric
  • ⅞ yard [0.8m] each of two different fabrics for HSTs (blue and red)
  • ⅝ yard [0.6m] each of two different fabrics for Quarter Square Triangles (yellow and green)
  • ½ yard [0.5m] for binding
  • 3 yards [2.75m] for backing

Marvel Avengers Kids in Action with complementary solid color fabrics.

Today, I’ll demonstrate one of the three methods I use to make HSTs. This method takes us back to the basics. There are two HSTs on each side of the accent fabric and quarter squares in all four corners of the block. On Thursday I’ll demonstrate my go-to method to make Quarter Square Triangles.

20 blocks are required to make this quilt. Each block measures 12” x 12” finished.

Completed blocks

Each HST measures 3” x 3” when finished. When cutting the fabrics for the HSTs, always add ⅞” to the finished size. In other words, cut the fabrics into squares measuring 3⅞” x 3⅞” each. If everything is perfect (the cutting, the marking, and the sewing), these measurements result in 3½” x 3½” unfinished HSTs.

In my case, while I strive for it, the result is never perfect. So, I prefer to err on the side of caution and cut 4” x 4” squares and trim after sewing. Yes, the trimming means taking an extra step but the resulting HSTs are perfect!

From the two fabrics I’m using for the HSTs, I cut 4” wide x width of fabric (WOF) strip. Then, I sub-cut each strip into 4” x 4” squares. I get 10 squares measuring 4” x 4”.

Cut 4” x 4” squares from a 4” x WOF strip of the blue and red fabrics.

Before going on to the next step, I’ll show you the marking tools I’m using this week. I often use Clover Chaco Liners. Why? Because I love the fine line they make, and the line easily rubs off the fabric with no effort. They come in regular and pen styles in white, silver, blue, yellow, or pink. Once empty, there are refills available for both liner styles.

Note: Although I’ve never had issues with Chaco Liners, all fabric marking tools should be tested on the fabrics to ensure the marks left will brush or wash off.

Chaco Liners by Clover.

Now, onwards!

For the next step, pair red and blue fabric squares, right sides together. Using a Chaco Liner, draw a diagonal line on the wrong side of one of the paired fabric squares. With lines drawn, sew a ¼” seam on each side of the diagonal line for each pair.

Note: Unless otherwise mentioned, all seams this week are ¼”.

Draw a diagonal line from corner to corner on the wrong side of the fabric and sew a ¼” seam on both sides of the line.

After sewing all seams, cut along the diagonal line, press open and trim the result to measure 3½” x3½”.

Cut sewn squares along the diagonal line, press seams open and trim to 3½” x 3½”.

Today, I introduced Clover Chaco Liners. They come in five colors, so there’s always a color that will be visible on any fabric. They are easily applied and equally easily removed after the seams are sewn.

Tomorrow, I’ll demonstrate using the Chaco Liner again as I feature another HST-making technique!

This is part 1 of 5 in this series

Go to part 2: 5 easy steps for making multiple Half Square Triangles at once!

Related posts

Summertime Streetscape Wall Quilt | additional design options

Summertime Streetscape Wall Quilt | beauty is in the details

Summertime Streetscape Wall Quilt | making roofs, windows, and doors!


Carol Jones-Packwood January 10, 2022 - 5:31 pm
Where do you buy the Clover markers?
Paul Leger January 10, 2022 - 5:36 pm
Hi Carol, I get them at one of my local quilt shops.
Alison January 10, 2022 - 1:06 pm
In the last step for trimming the hst should it be trimmed to 3.5 to finish in the quilt at 3”?
Paul Leger January 10, 2022 - 2:02 pm
Thanks Alison for picking that up. I'll get it corrected.
Add Comment