Topstitching is an great way to emphasise a construction detail, hold seam allowances flat, hold interfacing in position, or to add interest to plain fabric. It also reinforces seams, and I heard that topstitched garments require less ironing!
I’m a bit of a topstitching evangelist these days -I really love the look of it- but when I was a fashion student I was anti-topstitching. I preferred a totally clean look with no visible stitching whatsoever. I can’t pin down exactly when I changed, but it’s only been about the past five years that I’ve tried topstitching thread.
I use Gutermann topstitching thread or strong upholstery thread. I prefer upholstery thread because it seems to be less prone to abrasion as it flows through the machine, but it has a narrower range of colours. I used topstitching thread for my Jeans Recycling project, and this skirt last autumn.
To set up:
Use regular thread in the bobbin and the topstitching thread for the upper thread.
Install at least a size 14 (90) machine needle, if not a 16 (100).
Whack the machine on the longest stitch length -yes, I know you use that for basting, but topstitching thread looks best with a long stitch. Shorter stitches tend to bury themselves in the fabric.
I find I don’t need to change the machine’s tension, but you might.
I have to say my machine hates topstitching thread, even though it has a fair bit of grunt compared to other machines. It sounds like an old mixmaster as it chomps through the fabric. Stitching backwards is out of the question for the poor thing. Instead, I leave long ends and tie them off and/or sew them in. Straight stitch is a surer bet than zig zag; if one of the zigs or zags don’t catch then the seam doesn’t look right.
Have fun stitching!