Color Burst Cathedral Window Block PDF Download Block 6 of 9 in the Cathedral Window Quilt-a-Long. Block size is 12-1/2” square unfinished. Use a 1/4” seam allowance unless otherwise indicated. Finished quilt will measure 36“ square. Use Legacy™ by Pellon® 100% Natural Cotton or Soy/Cotton Blend Batting for a beautiful finish. This quilt block is so simple a beginner or an expert will be able to do it in a short amount of time.