This is almost certainly a pressing issue. If the back hangs in waves, then someone pressed the kilt incorrectly. Someone probably laid the kilt out on an ironing board, let the pleats splay, and pressed away without knowing what they were doing. The pleats have to be pressed the same width from the bottom of the fell to the bottom of the kilt, not splayed. Dry cleaners are notorious for pressing kilts badly (which is why you shouldn't have a dry cleaner press your kilt).

This is actually a tough problem to solve, because it's hard to "re-train" the pleats. You really need to first try to press out all of the pleat creases that are there right now (i.e., take the pleats _out_ of the kilt). Lay the kilt on the ironing board, pull a small section so that it is absolutely flat (no folds), and press both sides with lots of steam, a damp press cloth, and a clapper (a piece of 2x4 is good - it forces the stem into the fibers to relax them).

Once all of the pleats are pressed out, then you really have to baste the pleats in where you want them. Make absolutely certain that the pleats are the same width at the bottom of the kilt as they are at the bottom of the fell, and make sure that the stripes are correct and match what you see at the bottom of the fell (the stitched part of the pleat). Baste at the bottom of the kilt and then along lines not more than 4" apart between the bottom of the fell and the bottom of the kilt. It's not as much work as it sounds, actually.

I hate to say it, but if you skip the basting step, you're just going to wind up with the pleats slipping back to where they were pressed before. So, take the time to baste.

Once the kilt is basted, press both sides with a steam and a damp press cloth. Use the clapper again. Let the kilt dry thoroughly before taking out the basting stitches.

Barb