My great uncle worked in a factory that made parachutes early in WWII. Parachutes were first made of silk, then later silk nylon blend. Cotton would seem on the heavy side for a parachute, but I am certainly no authority on that subject.
When I was starting out in vintage WAY decades long ago, we collectors and dealers used the term "parachute silk" to describe garments that were actually made of old cast off or damaged silk parachutes. Oh, that was so long ago.........
I recall in the late 70s and early 80s, some club wear and evening type womens jumpsuits (the ones that resembled flight suits) were often made if a very thin silk similar to China silk, and it was sometimes called "parachute silk".
Of course, your blouse is much older than 1970s.