I’m so excited to share my method for inserting lace into a curved seam (such as a princess seam). For my blouse, I used this dusty peach handkerchief-weight linen and floral ivory insertion lace, though there are many, many options for both linens and laces, both online and in-store!
After seeing one of the cover shots for the Hayden pattern, and making a couple myself (two versions here), I really wanted to insert lace in the seam lines on the front and along the hem. The style lines are curved, though, so the typical way of inserting lace had to be tweaked a bit.
Usually, insertion lace is applied on an uncut, unseamed piece of fabric. The general steps are: sew along both lengths of the insertion lace, then cut through the fabric on the wrong side and press the fabric open. On the right side, using a narrow zig-zag stitch, sew along the edge of the lace again (which catches the fabric on the wrong side) and the trim the fabric on the wrong side, close to the stitches. Insertion lace can also be inserted into an existing seam, before sewing the seam and after taking into consideration the added width of the lace.
However, for this blouse, the seam in which I wanted to put the lace was a curved princess seam along the front. Instead of inserting the lace before sewing the seam, I did it a bit differently: