Modern Fat Quarter Quilting with Half Square Triangles (HSTs)
Making A Half Square Triangle Quilt
Modern Fat Quarter Quilting with Half Square Triangles is an amazing adventure in color and design. Deciding on focal and background fabrics sets the stage for your new quilt top, but then there’s also the layout to think about. It’s incredible how a single, simple block can be so versatile and create a multitude of different wonderful layout options. This little block can create stars and stripes in an easy layout or optical illusions with more elaborate designs. As the designer, you choose your favorite!
Making Half Square Triangles with Precuts
Whether you use fat quarters or other precuts to make your half square triangles, you’ll have plenty of design options to choose from. Now consider the countless fabrics choices. Choosing bright prints against a solid background will be a completely different look than black and white graphic prints with a color background. How do you begin to choose?
While this easy block allows a beginner to piece a quick quilt, the countless intricate layouts created with a single half square triangle can be very challenging when attempting to achieve a complex design. Looking at an asymmetrical ‘Around the World’ quilt can be mesmerizing. This is probably my personal favorite because it can be changed up in so many ways. But that’s not today’s project.
Modern Fat Quarter Quilting with Half Square Triangles Color Selection
Today is about getting started. The large 9” Half Square Triangle blocks for this quilt will make a big statement. The fabric required will be 8 print fat quarters and 8 background fat quarters. Each will be cut into an 18” square, then sewn and cut into smaller triangles using the Magic 8 method.
The fabric selection comes first. Bright colors with vivid contrast will make a simple chevron quilt quite striking to look at. My fabric selection is batiks and I have plenty on hand to choose from. Colors will range from turquoise to bright greens with yellow highlights for contrast. The background will be a blended turquoise and purple fabric that coordinates and carries the predominant, focal turquoise color.
Some Half Square Triangle Methods Require Caution
As with all things quilting, there are so many assembly options to choose from when it comes to half square triangles. My favorite is the ‘Magic 8’ method. It’s a quick and easy way to make a lot of half square triangles at one time.
While an HST is just a square made up of two triangles, there are some factors to consider. Triangles in general can pose a challenge because their long edges are cut on the diagonal. That diagonal is called the bias. If you were to take a fabric square and pull it from side to side at the middle of the side edges, you would get a lot of resistance against your pulling. The fabric won’t stretch in that direction. Now try pulling from corner to corner and watch that square warp. Imagine sewing a seam along that stretchy bias edge. There’s no easy way to get a nice square quilt top with blocks that stretch.
The beauty of the Magic 8 method is to sew first which stabilizes the bias seam then cut it. This way the seam is already sewn when the blocks are cut. The bias edges are secured and won’t stretch when the quilt top is being assembled.
Magic 8 Half Square Triangle Method
What is a Half Square Triangle
Half Square Triangles are a simple block but can be used so many different ways. The only quilt block easier than a Half Square Triangle is an uncut fabric square that is simply sewn to another. Now cut that fabric square on the diagonal from corner to corner to create two triangles. There you have it, an HST. It has one large 90-degree corner and two 45-degree points. Fortunately, there are many easier ways to make them than one at a time.
How to make Magic 8 Half Square Triangles
How do you make half square triangles eight at a time? The first step begins with two fabric squares. In this example, the focal fabric is on the bottom with the right side facing up. The background fabric is placed on top with the wrong side up, so the squares are right sides together.
If your fabric has any large wrinkles or folds, press them flat before starting the first step. This is important to keep your cut triangles nice and square with no wonky edges.
Notice the diagonal lines drawn on the top fabric from corner to corner. These lines are the cutting lines, but first the ¼”seams need to be sewn on each side of the line. With larger blocks like these 18” squares, I prefer to use a few pins to keep the squares lined up. First stitch a ¼” seam to one side of the diagonal line. Then stitch a 2nd ¼” seam along the other side of the same diagonal line. Now do the same for the other diagonal line. That’s the extent of sewing your HSTs.
How to Mark Cutting Lines of Half Square Triangles
This is the easiest step of all. Using your long ruler, draw a diagonal line from one corner to the opposite. Now do the same for the other two corners. Place a pin in each corner and one in the middle to keep both fabrics in place while you sew.
Not All Fat Quarters Are Created Equal
Not every fat quarter will measure 18” x 20” so be prepared to adjust. If some of your fat quarters fall short of the full 18”, just get the biggest square you can and make sure they all measure the same.
In the example above, I have also shown how to to use two 9” strips of fabric in place of an 18” square. One of the fabrics I wanted to use was cut at a quarter yard across the full width of the fabric. I simply drew the diagonal lines from the center to the corners and continued as described below.
You can take this a step further and use 10” precuts by drawing a diagonal line, sewing and cutting the block into two HSTs. As you can see, making HSTs is incredibly flexible so choose what method you like best, or what works with the size fabric you have on hand. This is a great technique to use for lots of different quilting projects.
How To Sew Half Square Triangles
Beginning at one corner of your marked and pinned block, line up your needle with the diagonal line. Stitch a ¼” seam to one side of the diagonal line. Then stitch a second ¼” seam along the other side of the same diagonal line. Now do the same for the other diagonal line going in the opposite direction. That’s the extent of sewing your HSTs.
How To Cut Half Square Triangles
The next step is to cut these large squares into 8 smaller triangles. I recommend making the cuts for one block at one time instead of stacking them all together. Since the diagonal cuts are on the bias, cutting them individually keeps all the straight edges lined up properly. While the double seams help keep the block square, the natural shifting of stacking and cutting multiple blocks is difficult to control.
There are four cuts made to each 18” block to create eight HSTs. Keeping the fabric in place, make your first cut from top to bottom. Center your ruler over the fabric square and cut from the top edge to the bottom edge. Then turn your ruler side to side, centering it over the fabric square. Make your next cut from one side to the other side. You now have 4 blocks.
Place your ruler’s edge within one of the diagonal seams you sewed. Make a cut from corner to corner, keeping you ruler centered between the stitching lines. Your second cut will be the opposite diagonal seam. These last cuts create eight individual HSTs. Congratulations, you did it!
How to Cut Really Big Half Square Triangles
The diagonal cut on these larger 18” blocks will exceed 24”. Since your largest ruler probably isn’t longer than 24” like mine, we need to make a bit of an adjustment. Make your first cut in the center from top to bottom, then the second cut in the center from side to side. Now you can easily cut each triangle individually.
Both methods worked for me but making the diagonal cuts on the individual 9” blocks was a lot easier than trying to span the entire distance without a yardstick!
Do I Need to Square Up A Half Square Triangle Block
Yes, you really should. This next step is a bit fussy, but don’t skip it. Squaring up each block is important to keep your diagonal seams lined up correctly when you assemble your quilt top. This bit of time will give you beautiful corners!
This 18” block results in eight 8 ½” HSTs but may vary a bit depending on your actual seam allowance. The Important point to remember when squaring up your HST is keeping the diagonal seam lined up with the 45-degree line on the ruler. In the following diagrams, I placed a strip of plastic tape over the 45-degree mark and drew a red line so you can see it better.
How to Size Up A Half Square Triangle Block
Using your cutting mat, measure a few squares and get an idea of the size you’ll be working with. If you used exactly ¼’ seams your blocks will be trimmed to 8 ½”. If your seams were a bit bigger, that will adjust the size of the block you’ll be trimming.
How to Square Up A Half Square Triangle Block
Now that we know the square size, it’s time to get the first square corner made. Find the 45-degree line on your cutting mat. Place the diagonal seam of your block directly on top of that line. Notice in the photo that you can see the line extend from both corners of the block which indicates that the block is square with the mat.
Time to Make the Cuts
Using a square ruler at least as large as your block, cut the bottom and side edge to create a perfectly square corner. Be sure the block doesn’t move around when you place the ruler on top. The 45-degree diagonal line of the square ruler will be directly on top of your diagonal seam, which is on top of the 45-degree line on the mat. This is a triple check method that makes it hard to miss the cut we want. Take your time to measure twice and cut once!
Line up the 8 ½” lines of your square ruler along the two straight edges you just cut. Make sure your 45-degree lines are lined up with your diagonal seam. Measuring from the corner that was just cut, trim the opposite sides for a perfect 8 ½” block. This is where a turntable cutting mat comes in very handy otherwise either you or the mat will be turning from one side to the other between cuts.
You now have eight perfectly square HSTs. Repeat this process for all your blocks and you’ll be ready to layout your quilt top. This is where the real fun gets started.
How to Layout HST Blocks
There seems to be no end to the layout possibilities of this simple little square. For this quilt I intentionally made large blocks to create a chevron pattern with a big impact. Since each fat quarter makes eight squares, that’s the size quilt top I decided on. With eight fabrics, that’s 64 blocks for an 8 x 8 block layout. The chevron pattern requires two rows to complete the design, therefore I need to combine two colors for each row.
After pairing up my blocks, I tried a couple different combinations to find what I liked best. Rather than making one chevron block with a single fabric, I chose to alternate the fabrics, so they blend across the row.
Contrast is a design element to consider in every quilt. The bright yellows in these fabrics make a big impact and bring more focus to the chevron design. I love how the green and yellows play off each other and look so good against the blue background. This quilt falls into my favorite tropical color scheme that I use a lot but would look great in many other colors as well.
How to Sew Your Magic 8 HST Blocks Together
How to Sew Your HST Blocks Together
An important step to making this half square triangle quilt is to keep your points and seams lined up. Since we took to the time to square up all the blocks, this is actually much easier to achieve than you think.
First, as you are sewing your blocks together into rows, using at least a ¼” seam. Here it’s okay to take just a bit wider seam than normal. This extra bit of seam allowance brings the peak of your point just a smidge below the seam line going in the opposite direction for the next step.
Now sew your rows together and as use no more than a ¼” seam allowance. You’ll notice as you’re sewing your rows together, your stitching is passing just above the sewn points from the previous step. This keeps your point nice and sharp instead of getting cut off.
A Sewing Tip That Makes A Noticeable Difference
Additionally, be sure to nest your seams so they fit snug and will lay flat. Remember that nesting seams refers to sewing across where two opposite seams match up. Turning each seam allowance opposite from each other allows for a snug fit and a perfectly matching seam line on your quilt top. Little steps like nesting seams will improve the appearance of your finished quilt top!
Of course, I’m already thinking about how to add a border with the leftover fat quarter strips. Some smaller HSTs would be perfect and I can’t wait to show you when it’s finished!
I hope you’re ready to try this HST block and create your own beauty. There will definitely be at least a couple more HST quilts in my future because there are more layouts I really want to try. Using 10” squares seems like a very easy option. I wasn’t sure about using such big blocks, but I really love how this looks. A holiday layer cake would make a beautiful HST quilt, don’t you think?
Here Are Some HST Layout Ideas
Have fun quilting and Create More Beauty in Your Life Every Day!