By now you may be getting the feeling that the half square triangle unit features quite a lot in quilting. In fact it might be the most commonly used patch in a quilt block, second only to the square. Our block this time is the Mosaic block and yes, you’ve guessed it, this block uses many half square triangles. So, let’s get making…
MOSAIC QUILT BLOCK
Finished Size 12″ (Unfinished 12-1/2″)
Mosaic quilt block comes next and is made entirely from Half Square Triangles. This is a great block for perfecting your skills and getting to grips with perfect points. So, grab a cuppa, take your time and enjoy the process.
CUTTING
I have made this block using two quick methods of making Half Square Triangles (HST) and made them a little larger so they can be cut to a perfect size. We will end up with four extra HST to add to our stash but making them this way is by far the quickest. If you prefer, make two ‘four at a time units’ and a ‘two at a time unit’ instead, I’m just showing you how I made this block.
There are lots of triangles in this block so, if you have trouble with stretching, I recommend using a quilter’s spray starch like Best Press to stiffen the fabric. You will need three, contrasting fabrics as well as the background fabric.
A. Two 8-1/4″ x 8-1/4″ squares (white)
B. One 8-1/4″ x 8-1/4″ square (red)
C. One 8-1/4″ x 8-1/4″ square (flower)
D. One 5-3/4″ x 5-3/4″ square (white)
E. One 5-3/4″ x 5-3/4″ square (turquoise)
The background fabrics for this block are A, & D.
BLOCK ASSEMBLY:
- All seams are 1/4″ and I use a stitch length of 1.8.
- As a rule, you would press your fabric seams towards the dark side (darker fabric) but not always. I finger press my seams before pressing with an iron. This allows me to change the seams’ direction if needed without stretching my fabrics.
- In bulky areas press your seams open as this will help reduce thickness.
We are going to begin by making eight Half Square Triangles at once using the ‘Eight at a Time’ method also known as ‘Magic 8’. These HST aren’t quite as stretchy as the ‘four at a time’ HST as all the triangles edges are cut on the fabrics straight of grain instead of on the bias. We are going to make them slightly larger and then trim them to size for accuracy. This is a really great, super quick method for making multiple HST.
Take one of your 8-1/4″ x 8-1/4″ white fabric squares A and draw two diagonal lines on the wrong side from corner to corner. Then place on top of your 8-1/4″ x 8-1/4″ red fabric square B with right sides together (RST).
Line up your edges and pin your fabrics together to stop them from shifting and sew 1/4″ away from each side of both your diagonal lines. You should now have four stitched lines.
Next cut your 8-1/4″ unit in half through its centre point. Your rulers 4-1/8″ line should run along its edge. Then repeat Horizontally. Check your ruler is straight and centred before cutting.
Finally cut along your drawn diagonal lines. You should now have eight HST but you only need six, so put the spares in your stash for another project.
Open one of your HST and finger press your seam to the dark side and set with an iron. Then trim to 3-1/2″ by placing your ruler’s 45° diagonal line along your seam line, squaring up your block, and trimming away the excess fabric. Now repeat until you have six perfect HST.
Take your remaining 8-1/4″ x 8-1/4″ squares A and C and make another six HST using the eight at a time method. This time press your seams towards the white fabric.
Next we are going to make our final four HST using the ‘Four at a Time’ method.
You will need your 5-3/4″ x 5-3/4″ white and turquoise fabric squares D and E to make four HST. Place both fabrics with right sides together (RST) lining up all the edges then stitch all the way around the square with a 1/4″ seam being careful not to cut the corners. If you are not sure where to turn at the corners, draw diagonal lines on your lightest fabric square and turn when your needle reaches each of the lines.
Now cut the unit diagonally (on your drawn line) from corner to corner in both directions cutting the unit into four triangles.
Then just as before open your HST, finger press your seam to the dark side and set with your iron. Now trim your HST to 3-1/2″ by placing your ruler’s 45° diagonal line along your seam line, squaring up your block and trimming away the excess fabric. You should have 16 HST (excluding extras).
Now lay out all your HST to form the Mosaic quilt block. Make sure that everything is pointing in the right direction, it’s very easy to sew things the wrong way round.
Keeping your fabrics in order, sew them together one row at a time, taking care to nest your seams and match your points. Finger press your seams in the direction of the arrows before fixing with an iron.
Finally sew your completed rows together pressing your seams open. Don’t forget to match your points and nest your seams together as you go.
If you have sewn your block together accurately it should measure 12-1/2″ square but if you need to trim it make sure you leave 1/4″ seam allowance on all your points.
You have just completed your sixth block.
