When a professional, clean finish is needed for a corner of fabric, mitering is usually the best solution. Ideal for flags, tablecloths, runners, and boxy clothes like jackets, mitered corners are a sign of high-quality workmanship and are often found on couture items. Yet while mitered corners may look couture and therefore difficult to sew, once you understand how they work, they aren’t complicated or time-consuming to make. Practice your first mitered corner on scrap fabric, and soon you’ll be whipping them out in no time at all.
Press under one-fourth inch on both the bottom hem and side hems, creating an edge finish.
Press up the bottom hem.
Unfold the bottom hem and press in the side hem.
Fold the bottom hem back up and with two pins, mark where the inside edges intersect. One pin should go through each fold at the inner corner.
Unfold the fabric, opening up the corner.
Fold the fabric diagonally with the right sides together, aligning the pins.
Draw a diagonal line from the pins to the inner corner, using a fabric marking pen or a tailor’s pencil and a ruler.
Stitch through this marked line, backstitching at the beginning and the end of the seam.
Turn the corner right side out to make certain you’ve stitched it correctly. The corner should look mitered.
Turn the fabric wrong side out again and trim the seam to one-fourth inch. Press the seam open.
Stitch the hems in place along the inside folds, pivoting the sewing machine needle at the corners.
Press under a scant one-fourth inch on both the bottom and side hems.
Press under another one-fourth inch on both the bottom and side hems.
Unfold the corner. Using fabric shears, cut off the pointed end of the corner.
Press down the raw edge of the corner one-fourth inch.
Fold each hem back in place; a mitered corner will appear. Secure the hems in place with machine stitching.
The couture method is appropriate for all applications, especially clothing. For simple items like napkins, the speedy method may be preferred.