Galoots

I have a wooden spar plane. The mouth is a bit big, but otherwise It's
in great shape. It has a tapered iron that's pretty pitted near the
cutting edge. I started flattening the iron on a diamond stone using
water as the lubricant. It was flattening OK, but felt it was going to
take forever and a day to get out the pits, especially in the corners.
So I wiped off the blade a couple of times on my shirt (that's what
shirts are for) and went and got my sandpaper, two minutes tops. I
came back and about a third of my iron which I had just flattened had
surface rust on it.

What's the speed of rust?

I know on a molecular level as soon as water hits steel you've got
rust. But should I be able to see it in that short of a time?

Another thought, does iron (the material) rust much faster compared to steel?

This iron (the blade) seems really short, and I wonder if all the steel is gone.

Thanks,
Chris