Top: When quarter-square triangle units are made from two identical half-square triangle parents, the resulting patchwork squares are identical and symmetrical.
Middle: Substitute a plain square for one of the pieced parent units to make units with two quarter-square patches in one half of the square and a single triangle in the other half. Resulting units are mirror images of each other.
Bottom: Use two different half-square triangle parents to make the quarter-square triangle units. Resulting units are mirror images of each other.
Look back at the star block illustrated on page 1. The parent units were not identical, but because they each share one a fabric, the resulting units are identical and symmetrical.
Will mirror image units work with your pattern?
- If you're making a scrap quilt with a large assortment of randomly arranged patchwork, mirror image units will work fine, and can actually enhance the quilt's scrappy appearance.
- If your quilt uses certain colors and fabrics in specific positions, only one unit in each quick-pieced pair will be used.
If some units cannot be used, weigh the advantages of quick piecing vs. sewing individual triangles together to create the patchwork you need. For instance, if I were making small triangle-square units, I would probably opt for the quick-pieced method simply because it eliminates the need to handle tiny triangles. I would throw the extra triangle squares into a patchwork bin and use them later in another project.
If you decide to assemble quarter-square units from individual triangles, remember that the fabric's straight grain should be parallel to each triangle's longest edge. Quarter-Square Triangle Cutting Instructions