One of the hardest fabrics to pleat, at least in my humble opinion, is silk dupioni. Silk, by its nature, is a strong fiber, closely woven thus making the process of feeding through the smocking pleater rather a chore. For awhile now, I have been pleating using the following process. Roll the silk onto your dowel for pleating. Align the edge to slowly start it through the rollers of the pleater. Allow the pleated fabric to "pile up" on the needles, then with your steam iron, give the pleats a blast of hot steam. Then with a small hair dryer, blow the steamed area dry. Now you can gently pull the pleats off the needles and begin the process again. This process does give you nice crisp pleats without the slubs of the silk giving you a problem, which by their nature makes the pleating look "bunchy".
But I had a customer, today inquire about using the German Interfacing with the pleating of the silk dupioni. She had read in the book or article that she was planning to use for her garment design, that putting a fusible interfacing on the fabric before pleating would help with the process. When she emailed me to ask if the German Interfacing would work, I took her up on the challenge. I told her I had only used the fusible interfacing at the END of the smocking process. I would steam a piece of fusible interfacing the size of the completed smocked area on the wrong side of the fabric. Steaming carefully as to not crush the pleats. Then because I had been doing a full smocked bodice, I would stay stitch the outline of the bodice. The fusible interfacing in this case would help to stablize everything before you cut out the smocked bodice area in preparation of completing the construction of the garment.
The German Interfacing is a wonderful, lightweight interfacing that is very nicely used on baby items where some stablization is needed for buttonholes, plackets and such. But it worked VERY well to give the silk dupioni a lovely rounded pleat, much like you get when pleating cottons. I have taken a picture of the wrong side with the interfacing fused to the silk, then pleated a few rows of the silk and included a picture of the resulting pleats. I can see that this is going to be EXTREMELY helpful when you are pleating over 16 rows!
GIVE IT A TRY!
