Bob in Australia--yes, I am referring to the rubber carriers as the blades. You appear to have the correct "closed" variety. Few of our 230/250 visitors did.
Doug, if you could email me a copy of that article, I'd appreciate it. If I understand correctly from your condensation, it seems that Frank called the satin variety "painted"? Remember we had shiny chrome plated, closed; satin chrome, closed; satin chrome, open (the current variety from Mercedes) or skeletonized, and then painted black versions which are what you can get or order from any Bosch dealer, but not from Mercedes.
Early skeletonized blades had a metal insert where the arm clips on; current versions have a black plastic insert.
Bob Possel, post a photo of your wipers, and we'll check them!
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored