One of my favorite aspects of teaching workshops is that it makes me really think through what I do. In the process of preparing to teach the Sunburst workshop with the Las Vegas Modern Quilt Guild a little over a week ago, I was making samples to show my process for making quarter-square triangles (QSTs), and I realized that I haven’t discussed QSTs or shared this particular tip on my blog yet. So, let’s take a look!
First, let me give a top level summary on my approach to making QSTs.
- Begin with (2) untrimmed HSTs. Press the HST seams to the side. In the example illustrated above, each HST contains navy, so the HSTs were both pressed toward the navy.
- On the wrong side of one untrimmed HST, mark a diagonal line perpendicular to the sewn seam line.
- Place the untrimmed HSTs right sides together, and make sure the seams nest neatly.
- Sew a scant ¼” on either side of the marked diagonal line.
- Cut apart along the marked line.
- Press seams open.
- Trim to desire size.
To know what size square to start with to make the initial untrimmed HSTs (if making the HSTs using the two-at-a-time method), I recommend adding 1½” to the finished size block. So if you want a QST that will finish at 4″ square, start with 5½” squares to make the untrimmed HSTs and trim the QST to 4½” square.
Which brings me to my tip: when marking the diagonal line on the wrong side of one of the untrimmed HSTs, I do not suggest marking the line from corner to corner of the HST. Because the HST is untrimmed, you cannot be sure that the two points are perpendicular to the sewn seam. Instead, I recommend lining up a ruler with the sewn seam (large red oval above) and sliding the ruler along the seam until it also intersects with one of the two corners of the untrimmed HST, which is the white corner in the photo above. Then mark the diagonal line.
As you can see in the above detail photograph, the diagonal line might not run perfectly through the second corner, but that is okay. It is much better that the marked line be perpendicular to the sewn seam. By marking the diagonal line perpendicular to the seam line, all four triangles of the QST should come out to be the same size, so after sewing a scant ¼” on either side of the marked diagonal line, cutting, and pressing, you will find that the QSTs sewn using this approach, rather than marking corner to corner on an untrimmed HST, will be easier to trim square.