I am supposed to see what exactly on that low-resolution picture of an Imperial Officer's hat?
Pictures of Jerjerrod in ROTJ are the best place in the OT to see anything of the gap between hat body and flap. There are more in ANH (my preferred reference), but they're less clear. I seem to owe you half an apology -- dug back through Star Wars Screencaps and caught something I'd previously missed. It's not bias tape, per se. But from what I can see in grabs like this one:
...It looks to be a 2" wide strip of the hat fabric, cut square rather than on the bias, on Jerjerrod's cap and, presumed by extension, the rest of the ROTJ hats. I can't project back through the previous films -- especially ANH, as those hats are definitely cut slightly taller than the ESB/ROTJ ones, and their construction must be looked at separately, since they're not reused later. The best frame-grabs from ANH, e.g. --
-- show nothing like what Jerjerrod has on his hat flaps, which is the basis for my original assertion. Even then, it wasn't until I was looking for clearer pics of Jerjerrod that I spotted that edge in a few frames. So while I can accept that they might have taken that shortcut for ROTJ and possibly ESB, I maintain it's the facing folded over the seam allowance for ANH, which leads to...
Different screen-used hats had the grain in different directions - except for the edge. If the edge was folded over and not bias tape then the grain would be different at the top from the sides, which it isn't on any hat.
The black caps in ANH that can be made out clearly have the grain all running in the usual twill direction, matching the uniform jackets. Including the trim at the top. The couple officers wearing
steingrau caps the fabric grain isn't visible. For ESB and ROTJ, yeah, the grain is all over the place. That indicates to me they cut the pieces from any odd scraps big enough and didn't care about grain direction. The edging I figure they just took a foot-long cut of fabric and cut two-inch strips from it, selvage to selvage. It has to be that way for the grain to be the opposite of the typical twill directionality.
I know from sewing my own Imperial Officer hats that using bias tape is much preferable. It is the professional way to do it. Why would the same professional tailors at Bernams and Nathans that made the Rebel Hoth hats then not have used bias tape also for the Imperial Officers' hats?
I've learned both ways to do it. Each has its advantages. The advantage to the bias tape/trim piece approach is identical pattern pieces for the outer and facing. The advantage to the folded-over method is fewer pieces to wrangle. It does mean a separately-patterend piece for the facing, but it's not difficult to draft. Both are professional. It depends mostly on the desired end result. Bias tape is used as a cheat when the facing won't be seen, ever. The fold-over method when it will/might. I prefer the latter, as it gives a cleaner appearance under close examination, and it's no harder to sew (a case could even be made for easier, as stitching in the ditch is more optional than required).
I knew the Rebel Hoth hats had separate trim pieces (different color -- duh), but hadn't realized the sequel films' Imperial caps did, too. So thank you for the education and helping me clarify my position on this.
All the hat replicas I've ever seen people do, licensed or not, have been ESB/ROTJ. It is well known that too much of the costumes and props for ANH no longer exist for examination. I have never seen an ANH Imperial cap show up in a costume exhibit, book on the Archives, or reference for a licensed costume (Museum Replicas or ANOVOS). Even Brian Alinger's lovely-if-too-abridged book on the OT costumes shows non-ANH Imperial uniforms in the ANH section. About all we have to go on for those is frame-grabs and the rare piece that shows up at auction (I have seen
one ANH Stormtrooper officer uniform auctioned in close to twenty years of looking).