Stitch width of 0
Use DMC heirloom sewing machine thread when doing this for real and needle size#60, #65 or #70.
For the sample I will just be using normal sewing thread so you can see it easy in the photos and it will be a contrasting color for the same reason. But I will show samples at the end with the correct thread used so you can see how invisible it is with the correct thread which is thinner and matches the fabric and lace.
(UPDATE: there was some good questions in the first comment please read it and the second comment where I answer it for more information on samples and where to get supplies if you do not have a local source)
Cut 2 pieces of 100% cotton Batiste that are about 3 by 6 inches you don't need big pieces to test on
Starch (using clean iron, and clean board, also use spray starch)
- With wrong sides together. Straight stitch seam taking up 1/2 of your seam allowance. ( most seams in heirloom sewing are 1/2 inch for french seams so this would be about 1/4 inch from edge of fabric)
Note if you are using normal seam allowance which are 5/8 of an inch use the half rule of thumb.