When I am making period coats specifically the 18th century style with full skirts, there always is the question of what to put in them for structure and support.
The fabrics that we are given are what we have to work with and they can often be a challenge to work with.
I doubt that any of our modern fabrics have the body of some of those silks that were used then.
Most designers want the skirts of these coats to stand out and the trick is to find some kind of interfacing or interlining that will work. something with body that won't lose its oomph over time.
I have been using a sew in interfacing called "sew sure" for many years now. I find it fits the bill providing a lightweight and springy structure that lasts over time. It has a natural tendency to fold flat upon itself lengthwise (warp), but resists folding across the weft, so I cut it so the weft sits vertically at the front edge of the coat. It is also inexpensive, which helps because some of these coat skirts are quite large.
I have a woman's coat to make in a variation of the style of the men's 18th century coats. They are full skirted with pleats but ankle length. The skirts of the coat needed to be a kind of hybrid between the men's look and a woman's dress. The designer wanted the skirts to stand out but we didn't want the full structuring to come right up to the hip where the pleating and the flaring began.
So I modified the technique a bit, using the sew sure interfacing in the bottom 14 inches of the skirts panels. They couldn't just float inside, so I cut a layer of thin poly cotton and attached the sew sure to it and then flat mounted the inner structure to each panel of the coat.
Here is the back of the coat with the structure inside and the trim sewn on the back. I think it works to give the skirts body and make them stand out at the hem.
I notice a bit of rippling going on on the right side but I think it is just sitting strangely on the stand. Will check it tomorrow.
please forgive the picture quality I am literally snapping photos as I am leaving the studio, since the deadlines are pressing!