How to Piece the Easy Pinwheel Mosaic Quilt Block

Let's take a look at this variation of a mosaic block that I'm calling Pinwheel Mosaic. With only half square triangles and flying geese, the block goes together quickly. Let's get started!

Fabric Requirements for a 12" Finished Pinwheel Mosaic Quilt Block:

• Light/White: 4 - 4" squares
• Medium/Light Blue: 2 - 4" squares, and 8 - 3.5" squares
• Medium/Yellow: 2 - 4" squares
• Dark/Blue: 4 - 3.5" x 6.5" rectangles

Sewing Directions:

Half Square Triangle Units:

Step 1:

Using two of the Light/White 4" squares and the Medium/Light Blue 4" squares, make four Half Square Triangle units. Trim/square up the units to 3.5" square. You can find a tutorial for making a basic Half Square Triangle at https://fabric406.com/blogs/fabric406-blog/how-to-sew-a-basic-half-square-triangle-block

Step 2:

Repeat Step 1 only substituting the four Medium/Yellow 4" squares for the Medium/Light Blue 4" squares. I also have a tutorial for making multiple Half Square Triangle units at https://fabric406.com/blogs/fabric406-blog/two-easy-methods-for-making-half-square-triangle-quilt-blocks

Center Pinwheel Unit:

Step 3:

Lay out the Step 2 units as shown in the picture below. 

Step 4:

Sew the half square triangle units into two rows as shown below.

Step 5:

Press the seam allowances in opposite directions as shown in the picture below.

Step 6:

Sew the two rows together and...

Step 7:

Press the seam allowance. I've used the tweak/twirl/furl method for pressing. This method makes for a flatter block. You can find a better picture of this at https://fabric406.com/blogs/fabric406-blog/pinwheel-quilt-block-pattern

Flying Geese Units:

Step 8:

Using the four Dark/Blue 3.5" x 6.5" rectangles and the eight Medium/Light Blue 3.5" squares, sew together four Flying Geese units like the ones in the picture below. You can find my method for making a no-trim Flying Geese block at https://fabric406.com/blogs/fabric406-blog/how-to-sew-a-basic-flying-geese-block

Putting It All Together:

Step 9:

Lay out the Half Square units, the Center Pinwheel unit, and the Flying Geese units as shown in the picture below. From here the block goes together like an uneven Nine Patch block.

 

Step 10:

Sew the units into three rows as shown below.

Step 11:

Press the seam allowances toward the Flying Geese units.

Step 12:

Finally sew the three rows together and...

press the seam allowances away from the center of the block as shown below.

Conclusion:

This Pinwheel Mosaic block went together so quick! So satisfying to get a block done quickly. I should have used a darker fabric for the Dark/Blue so that it stands out more but...you never know until you try. The block also makes a wonderful secondary design when sewn into a quilt. Check out the layout options below.

Layout Options:

Here's the standard 4 x 4 layout. Love the diamond shapes that show up!

Here's the same layout but with a narrow sashing added.

Here it is in an on-point layout. Looks totally different. However, it could be easier to make two different blocks - one with the pinwheel and one with the square block.

And here's the on-point layout with sashing and cornerstones. I like this one too.