If you’ve ever had to hem a curved edge, you’ll know how tricky it is to turn, press and stitch it so that it looks neat and tidy. Curved edges are tricky for a few reasons. They involve a bias grainline, which causes the fabric to stretch out. Also, depending on the kind of curve you are working with, whether it be concave or convex, the fabric edge will be longer or shorter in length compared to the area it is being folded to, indicated by the red dashed line in the following diagram...
In the instance of a concave curve where the fabric edge is shorter than the area it is folded to, the bias grainline will stretch, allowing you to manipulate the fabric. If it is a severe concave curve, you can clip the seam allowance in order to prevent puckering.
In the instance of a convex curve, the length of the fabric edge is longer than the area it is folding to, so you have to manipulate the fabric to make the lengths equal.
Here’s a little tip for finishing curved edges...
Single Fold Hem
(I recommend that you finish the edge with a serge or zig zag before starting. This demo is left unfinished so that you could see the stitches more clearly)
Sew a baste stitch 1/8” from the fabric edge, leaving a few inches of thread at one end
Sew a second row of stitching at the intended seam allowance for the hem
Pull on one of the thread tails from the stitch closest to the edge, drawing the fabric just enough so that the folded edge lays flat onto the fabric
Distribute the gathers evenly and press
Turn the fabric towards the wrong side, pressing along the second stitch line. This stitch acts as a folding guide and helps in achieving a crisp and even fold
Distribute the gathers along the curve and press
Topstitch the hem within the seam allowance
Double Fold Hem
Sew a baste stitch ¼”away from the fabric edge. Sew a second row ½” away from the fabric edge
Turning the fabric towards the wrong side, press along the first ¼” stitch line
This helps to create a crisp even line to fold along the stitch
Press again along the ½” stitch line.
Topstitch along the hem within the seam allowance. Feel free to remove the stitching along the folded edge after the hem is finished