I know I'm a little late on this but I just wanted to say that I love all of the info! Thanks so much for sharing! I was so happy to see the materials list and D23 photos.
I'm going to start a Phasma build soon, and step one for me (being primarily a seamstress) is the cape (also cause I hope to finish the cape for the premiere and just wear it). Has anyone figured out any more detail as to what the coating is on the canvas?
Assuming no one has any ideas yet, I will probably just buy a bunch of potential coatings and start going nuts on all the canvas samples I sent for to test and see what combination of fabric and coating will get me closest.
I haven't seen any pre-coated stuff that looks close, with the exception of some oilskins (which I also got samples of). If anyone has seen anything that works/has any insight, I'd love to hear it.
EDIT: Because I realized I should at least put forward a theory. To me, it resembles old school military oilcloth/oilskin fabrics. Although that might be a personal bias, as someone who has done historical and steampunk costuming. So, my instinct is to treat a base cotton canvas with flax seed/linseed oil (but maybe more like how linen is normally treated by soaking it, although I'm worried about wringing out the canvas since it's so much thicker and more rigid than linen) and then coat it in wax/some other, more modern coating that will give it more of a sheen (because it's shinier than oilskin).