So before I forget how to do it, here is the technique I used for the narrow baby hem on the satin bridesmaid dress. I did actually start by experimenting with my narrow hem foot, but ditched that idea pretty fast when I realised that I have a huge learning curve ahead of me there. Something for another day...
I was inspired by a Threads article (Issue 145 "Bias on the Edge") on applying bias facings to armholes and I think it may be the same method used by Susan Khalje since she refers to 3 lines of stitching, but I am not sure as I don't have all her books (yet!). This method is only slightly different to my standard approach, but the results are far superior. Hopefully you can spot the difference, but below are samples of the old way (top) and new way (bottom).
You will need to test a sample to see how far from the finished hemline to put your first row of stitching (basically the width of the first fold, but the measurement will vary depending on the fabric). Anyhow here is the basic method with photos;
|Stitch a row of stitching just below the finished hemline.
|Fold on this stitching line and press.
|Stitch again very close to the fold. This is the extra row of stitching and it makes all the difference.
|Trim as close to the second stitching line as possible.
|Fold over and press again.
|Stitch again - I found the finish to be better if you don't stitch directly on top of line 2.
|Finished front side.