KathyRo, if you’re spinning “ in the grease”, with fresh off the sheep fleece, you really want to wash it after spinning, and before skeining. The yarn blooms a lot when the lanolin is washed out.

Even today, Aroostook County in Maine is a rugged and beautiful place populated by tough-as-nails New Englanders. No doubt doubly so back then.

Took me a while to figure out what that was on her head!

Boy I am having a tough time decoding what stage of yarn preparation is going on here. With respect to the caption writer, I doubt the wool was "aired". It's much more likely that it was dyed or bleached and hung out to dry.

The "large skein" configuration bears testament to that. Strangely though it looks like it's already been spun (if not plied). Wool that is ready to be spun is called roving and it's much fluffier than this. (See picture below.) However, if you are dyeing your wool a uniform color, it makes the most sense to do it while it's roving (aka "dyed in the wool").

Any other fiber enthusiasts out there with more mid-century experience than I have?

Airing before spinning? Sorry, the caption is in error. The photo shows already spun yarn.

Typically, after spinning and plying (twisting a second thread of spun yarn with the first), the plied yarn is then washed and hung in skeins (as shown) in order to set the twist.

After which, it is ready for weaving or knitting.