Half Square Triangles (HST)

Several of our blocks for the 2021 Quilting BOM are made up of Half Square Triangles (HST).  While we recommend one techniques, there are several techniques for creating HST,

• 2-at-a-time
• 4-at-a-time
• 8-at-a-time

It is always a good idea to try different techniques to find the technique that works best for you.  Sometimes you may only need one or two HST and other times you may need a dozen or more, so knowing how to do the different techniques will help you make them accurately and quickly. 

For example, you may need 12 matching HST, and you could do one of the following:

1. repeat 2-at-a-time,  six times
2. one 4-at-a-time and one 8-at-a-time
3. Repeat 4-at-a-time, three times. 

There are several techniques on how to Square-up your HST to make sure that it is the correct size.  The 2, 4, or 8 at a time methods do leave a little room for the HST to be a  little off the correct size, so it is always best to square them up before continuing. 

Another alternative is to purchase HST paper, that allows you to make as many as you want at a time.  My favorite it the “Triangles on a Roll” and they came in so many different sizes.    The nice thing with the HST paper is that there is not need for trimming your HST.  They come out the correct size each time, as long as you cut straight on the lines.

“Two at a time” – HST Method

When you only need two of the same layout of HST

Depending on the size of your HST, you will need one piece of background and one piece of color fabric.

Draw a line diagonally down the middle of the lighter color fabric.  Stitch 1/4″ on both sides of line. 

Cut down the center line, creating 2 HST.

This will create the two HST, you will need to square up the HST before using in your quilt. See “Square-up HST” for the different methods

“Four at a time” – HST Method

Depending on the size of your HST, you will use one piece of background and one piece of color fabric, placing front sides together.

Stitch 1/4″ along all four sides of square (red line is stitching)

Cut Diagonally from Corner to corner both directions (purple lines)

This will create the Four HST, you will need to square up the HST before using in your quilt. See “Square-up HST” for the different methods.

“Eight at a time” – HST Method

This method is great when you need 8 HST of the same colors.

Depending on the size of your HST, you will use one piece of background and one piece of fabric.

Draw a line from corner to corner on the wrong side on the lighter fabric, creating an “X”.

• Stitch 1/4″ on both sides of the drawn lines, creating a double X (Black lines)

• Cut vertical and horizontal halfway, and then cut along the drawn lines (red X).
  • (Cut on the Red lines in picture)

This will create the Eight HST, you will need to square up the HST before using in your quilt. See “Square-up HST” for the different methods.

“Paper HST” – HST Method using paper

You can purchase the Paper HST in different layouts by different companies.  I love the “Triangles on a Roll” because if I want 4 HST or 200 HST, I can pick the length of the paper and the number of HST that I want to use.  You can purchase “Cake Mix Recipe” that are great for using a Layer Cake to make HST.  

You can also print some off the internet, just make sure that you double check that the page printed the correct size, so that your HST are correct.  If you print from the web, I use “newsprint” to print on, as it is thinner and easier to tear off after cutting the HST.

Squaring-up HST

There are a couple different ways you can square-up the HST after you have created them.

You can press them open, and then use a regular ruler to square them up, or you can use a special ruler like the Quilt in a Day Triangle Square ruler, that lets you square them up before you press them, resulting in only having to trim once before you press them open.

Option 1 – Use a Triangle Square up Ruler, to square the block before you press open, easiest way. 

You align the size you need with the stitch line and then center the ruler on the fabric, then trim off both sides to the triangle.

Next step is to press open all the squares, by pressing the seam towards the darker side, then trim off the  “dog tails” on the corners.

Option 2 – Use a ruler to measure and square up the pressed open square.

First press open all the squares, by pressing the seam towards the darker side.

Use the diagonal line to do down the middle of your square. Look at where you square lines up on the size of your block. For example in this picture, I am working with a 3 1/2″ x 3 1/2″ HST,  I look to see that my lines match up at those line, both horizontal and vertical.  Then I trim off the excess.  If your square is a little odd shaped, you will need to square up two sides, and then rotate the HST to trim the other two sides.     

If you trim all four sides, you will have the “dog tails” removed, if you did not need to trim all four sides, you can simply trim of them off, to have a nice completed square.

I hope the list of different techniques and how to square-up HST will help when you are working on your blocks.