Whilst making bridesmaid dresses recently, one of the girls during her toile fitting voiced some concern about the sleeves, and whether they might fall off her shoulder, or have her bra strap showing. To ease her concern, I suggesting putting strap retainers in the dresses.
The sleeves on these dresses are more or less a pleated rectangle sewn into a strapless dress, giving the look of a short cap sleeve, or a very wide strap, whichever way you choose to look at it.
Never having actually had anyone take me up on the offer of using them before, I googled strap retainers to see if I could use the shared wisdom of the internet to help me with the best way to put them in. Alas, I came up empty, so had to use my own brain to devise the best method.
Each dress had a slightly different placement of the strap retainers, so I firstly found the top of the shoulder for each of the girls. For my rectangle, I doubled the width I needed and added seam allowance. I sewed the strap retainers in prior to sewing the seam.
With the press stud closed, line up the folded edge of the ribbon so that it sits just within the seam allowance of the sleeve. Open it out again, and stitch close to the edge of the ribbon.
Close the press stud again, and pin it in place so it won't slide around while sewing the side seam.
Complete the side seam, catching in about 1mm of the ribbon in the seam.
Understitch the seam to keep the underside of the sleeve sitting under, and ensure that the ribbon doesn't try to poke out.
Press your seam down. That's it!
Stitching down both sides of the ribbon on the strap retainer ensures that it won't be the strap retainer that you have issues with. Now you just need to remember to put your bra strap in the strap retainer when you put your dress (or top) on.