I have to confess that after handling a couple dozen straight razors, I know a wedge when I see one, but I cannot distinguish a quarter hollow from a half hollow or 3/4 hollow. I've looked at the cross-section diagrams but when I look at an actual straight razor, I can't really map the diagrams to it. Any tips on making these distinctions?

Another hollow question: I see the terms about full, extra and double hollows. I have an American razor stamped "double hollow" and it has that thickening of the blade before narrowing again to the edge, so I get double hollow. Do the full and extra hollow blades also have this or are they something else?

Many thanks for any help here!

best, Dan