Toncan Iron was their version of "Corten Steel" as weathering steels are generically known by today.
Full Pamphlet: https://archive.org/details/ThePathToSheetMetalPermanenceToncanIron_853/mode/2up
Check out the sketches on the first few pages. Reminds me of this:
https://www.bitchute.com/video/kyLoQ6zPfODy/
(post is archived)