A cathedral window quilt is a traditional quilt block pattern that frames squares of colourful fabrics in the background colour. The extra effort required to make the squares is offset by the fact that once assembled, the quilt is complete (no quilting or backing is required). Quilters typically cut squares and do the preliminary machine sewing and pressing steps in assembly-line fashion. The premanufactured squares are portable, making completion of the hand-sewn details easy to accomplish in spare moments and away from home.
Cut perfectly square blocks of the background fabric, ensuring that the sides of the square are aligned with the straight grain of the fabric. Calculate the size of the squares by adding 1/2 inch to twice the size that you want for the finished square. Use the finished square size to determine how many squares you will need to complete your project.
Cut perfectly square blocks of coloured fabric with sides 1/8 inch smaller than the finished block size. The "window panes" will be placed at the seams between the background blocks. For a quilt that is X rows by Y columns, the formula to determine the number of coloured squares that you need is Y times (X-1) plus X times (Y-1).
Fold the background squares in half, right sides together, and make a 1/4-inch seam along each of the short ends. At the folded corner of each seam, cut the corner from the seam allowance to reduce bulk when the square is turned to the right side. Open the seam and press lightly with the iron.
Match the seams at the two cut edges and pin with the right sides together. Bring the two folded edges of the seams together by folding in the opposite direction and pushing the midpoint of the folded edge toward the cut edge. Smooth the layers of fabric so they form a triangle with the cut edge at the top with the folded seam edges at the bottom. Pin along the cut edge, taking care not to catch the fabric that has been folded inside.
Stitch a 1/4-inch seam, stopping 1 1/2 inches before reaching the opposite side. Leave a 1-inch opening for turning and continue the seam to the end. Clip the corners of the seams to reduce the fabric at the points. Open the seam and press lightly with the iron.
Turn the square to the right side and carefully pull out the corners to form well-defined points. Press in place, making sure the squares are uniform sizes and their edges are perpendicular. The edges of this new square are aligned with the fabric bias, which is critical to forming the curves of the window frame.
Place the seam edges face up and fold the points of the square so that they meet exactly in the centre and press in place. The result should be a perfect square that matches your target finished square size. The seams and the opening should be completely hidden by the folded points. Press in place, pinning if necessary to avoid burning your fingers. The pressed creases mark the seam lines that you will use to join the pieces.
Pin two squares together with the seam sides facing out. Stitch along the pressed crease that forms a side of the final square. Continue to attach pieces until you have attached the number of pieces for a row. Repeat until all rows are created. You may choose to create smaller blocks to increase the portability of your project.
Pin two rows together with seam sides facing out. Stitch along the pressed creases that form sides of the final squares. Continue until you have attached all of the rows.
Fold the corners of each square along the creased lines and tack with tiny stitches at the centres.
Align the corners of a coloured square with the seam between two squares. This will form a diamond shape with the other two corners meeting the centre points of the adjacent squares.
Pull the midpoint of the background that aligns an edge over the coloured fabric. Pin in place so the background frame forms a curve with its widest point at the centre. The folded frame should completely cover the cut edges of the coloured fabric. Stitch in place with tiny stitches, catching only the curved frame and the coloured window pane. Repeat for each of the sides of the coloured fabric.
Add coloured panes to each seam until you have reached the border of your finished quilt. All horizontal and vertical seams will be covered by coloured windows. The quilt border will have a single row of background-coloured triangles pointing into the quilt along each edge.
Cathedral window squares are often used to construct fabric pieces for garments and other small items. For a simpler way to achieve similar results, try the faux cathedral window quilting technique. This method uses two circles, one of the background and one of coloured fabric, sewn with right sides together, leaving an opening. The circle is turned right side out and placed with the coloured side up. The curved edges are pressed toward the centre and stitched so the pieces form a square, with the coloured fabric framed by the background colour.
This quilting technique relies on geometry. In order to achieve high-quality results, pieces must be cut perfectly square to uniform sizes. Likewise, seams and folds must be precise. All of your folded squares should be a uniform size, forming right angles at each corner.