Gentlemen,
It's even more complicated than that. I echo Jeff's appreciation Steve: Fine work! And like you, I have yet to see a definitive example of pre-war in a sans-serif font, nor a WWII example in a serif font. BUT as your work, Steve, and Jeff's questions suggest, we're dealing with far more variability than simply "sans-serif vs serif." I doubt very strongly there would be any consistency, other than coincidental, from manufacturer to manufacturer. Absent U.S. govt regulation and until proven otherwise, I'm going to say they'd put their own moniker on there anyway they want.
I believe this is about branding (or lack thereof) more than anything else... aluminum producers wanted their respective brands featured prominently on their product to build mindshare. Companies vied for attention, and the one way manufacturers of otherwise indistinct sheets of aluminum could do that is with branding by stencil. You see "Alclad" enough times, it sticks in your head...
Can't quarrel with that marketing view, I've learned that about a thousand times and your point is well made, Mark.
Well agreed - 'variability' in type is something we've definitely seen - but key wording like 'ALCLAD' being a major constant, for sure. And it did stick - like the bacon
Bernays put on our breakfast tables, every self-respecting sheet metal mechanic has the term on the tip of the tongue (say THAT one really fast nine times)...
Just a guess, but it seems to me that in an area of practical need, 'style' of lettering was second to 'brand' in this case: use of raw aluminum is rather utilitarian - those who apply it on the line just 'need to know' what it is; so there does not seem to have been a huge worry over appearance and I have no idea who made the identifying stencil-rollers or how often they were replaced. But ensureing 'built to spec' is vital and it's clear that ALCOA (and one supposes Reynolds) ensured that a clear term was patented for the product, and the product clearly ID'd. Just a guess there.
We've seen enough variability in fact that while I understand what Steve says about what he's seen and hasn't seen, I don't believe we have a conclusive case as to what well may yet be found.
I have to say, after what I've looked at and studied, I for one would not be willing to cast 2-2-V-1 aside as some would seem to wish - it simply remains too rich a possibility in my view. I also believe there's much more to learn about aluminum markings and believe as we might do so that a great deal may be realized about just how variable that process may have been. To repeat - what I just saw in Steve's post here underscores that very thing, one more variation wrinkle in stenciling.
I hope the data points will keep coming.