Originally Posted by Bah Humbug

It gets deep - the metals alloyed with the iron, even in small quantities, have huge effects on the carbides (the bits that make it steel instead of iron) and huge piles of other metallurgical terms I barely understand. A very lightly-alloyed steel, for example, can have very very fine carbides and can be easily sharpened to a fine edge, but that edge can be so smooth it has a hard time "biting" into tough pepper skins. Hitachi calls those "white" steels. The "blue" steels contain more added metals like bits of chromium, vanadium, and tungsten, by my memory. This gives it carbides of varying sizes (and a longer edge life) that gives it a "toothy" edge that bites into tough skins. It's slightly harder to sharpen, and won't take the sort of edge a sushi chef would want.

The trick with stainless is it's gummy - when you try to sharpen it, it feels nasty on the stones. Worse, instead of easily grinding off a layer of steel, it rolls a gummy sliver of steel to the edge, where it hangs on and then just flips back and forth as you try to sharpen each side. It sucks. The newer stainless steels (R2 especially) are much better about that, but still don't feel as good and aren't as easy as non-stainless. It's worth it for some things like paring knifes and the knife I use for pineapple, though.