Triangles used in the four corners of a quilt have straight grain edges along their shortest sides.The straight grain flows parallel to the longest side of triangles used to fill in the remaining edges of the quilt top.
Fabric Grain Matters
To minimize stretch, it’s best to assemble quilt components with the fabric’s straight grain along edges that will be on the outer perimeter of a block or quilt, so there’s less chance of stretch as you work. This difference may not seem important, but it actually makes a huge impact on the stability of the outer edges of your projects.
Using Quilt Blocks for Outer Triangles
Quilters sometimes opt to sew partial quilt blocks to use as setting and corner triangles. This technique is used in many other quilt examples, such as pitchers for Tildy’s cabin quilt or the floating nine patch quilt. Partial blocks used for setting components must be drafted especially for their spot in the quilt. You cannot cut patchwork setting triangles by dividing a block into halves or quarters because triangles produced with that method do not include extra seam allowances and will be too small. It’s easier and far more common to cut setting triangles from quilting fabrics. The stretchy bias runs along a corner triangle’s longest edge and becomes stabilized when it’s sewn to a quilt block.
Corner Triangle Instructions
The tiny bit added when you round up is rarely noticeable when you sew the triangles to the ends of rows.
Parent Squares for Common Quilt Block Sizes
4-inch blocks: cut 3 3/4-inch parent squares6-inch blocks: cut 5 1/8-inch parent squares9-inch blocks: cut 7 1/4-inch parent squares10-inch blocks: cut 8-inch parent squares12-inch blocks: cut 9 3/8-inch parent squares14-inch blocks: cut 10 3/4-inch parent squares15-inch blocks: cut 11 1/2-inch parent squares
If setting triangles were cut like corner triangles, their longest edges would flow along the stretchy bias, making the outer edges of a quilt more likely to stretch out of shape before the project is complete.
Setting Triangle Instructions
Parent Squares for Common Quilt Block Sizes
4-inch blocks: cut 7-inch parent squares6-inch blocks: cut 9 3/4-inch parent squares9-inch blocks: cut 14-inch parent squares10-inch blocks: cut 15 3/8-inch parent squares12-inch blocks: cut 18 1/4-inch parent squares15-inch blocks: cut 22 1/2-inch parent squares
Once you’ve mastered triangles, try cutting more patchwork shapes.
