Thanks so much for all the great advice about how to fix my trapeze dress. I finally found a source of zips of the right style and length on eBay, so I’ve ordered one. Fingers crossed it does the job.
I’m using a very lightweight neoprene instead of the doubleknit the pattern recommends. It seems to be working out pretty well, but the frustrating thing is that the neoprene is black, and I’m sewing by artificial light, so it’s impossible to see any of the cool seam detail when trying them on. They just look like black leggings.
I did manage to get some photos of the lapped seams using the flash on the camera. The eagle-eyed may notice that the picture of the quadruple top-stitching below doesn’t match the technical drawing. I decided to omit the slits at the ankle.
Thin neoprene is fantastically easy to top-stitch. It’s stable, smooth, and very easy to mark with chalk. I made a paper guide for the curved top-stitching lines in the picture above and transferred the lines to the right side of the fabric using a chalk wheel. The chalk just wipes off with a damp cloth when you’re done.
For the lapped seams I marked the stitching and placement lines with chalk. I didn’t bother making templates for that but used my seam gauge. I used a few pins here and there to hold things together while I sewed, but they don’t seem to have damaged the fabric.
As well as the lapped seams there are also some regular seams. I sewed those using my machine’s triple stretch stitch for maximum durability. Pressing those open was something of a battle. I had most success when I pressed with a fairly hot iron and no steam, and then put a heavy book on top until they cooled.
Hopefully I’ll have some daylight pictures of the finished object next week.