Tom, I not anti-carbon, they just may not age well for me if I buy them in bulk (micro rust). Have you tried the Feather CS DE blades? If so, how were they? How many shaves per blade? (Their SS blades give me 2 great shaves only- that's why they don't make the cut for me.)
I just used a modern made Treet double edge blade in carbon steel. I used my Gillette Aristocrat and it gave me a phenomenal shave! The blade itself is black colored (odd looking) and says "a Treet for your face" right on the blade LOL. I am exceedingly pleased with this blade, and I'm keen to see how it does in some other razors. I always rinse and blot dry my blades between shaves, so I will be surprised if I'm troubled with rust, but we'll see.......
Just for purposes of information. I'm here reading this 8 years later (November 2, 2019) in the thread. I just checked Amazon and both the Treet Black Beauty and the Treet Classic are still available there. The Classics are pretty darn economical. The Black Beauties aren't bad either. Found some Treet Durasharps as well. Now...Back to reading!!
Old post, but since this thread got bumped up... Guessing rust not visible to the naked eye. Had that once on a NOS vintage three hole blade. Tugged something fierce. Looked at the edge under a 10X jeweler's loupe and it was covered with micro pitting from rust.