PMFJI --
That's iron oxide paste (similar to "jeweller's rouge"), about 0.1 micron. It's _really_ fine! Larry suggests using it for a final finisher.
Typical CrOxide paste runs about 0.5 micron.
Which suggests something:
. . . You might get a sharper edge if you went:
. . . 8K Norton --> 0.5 micron CrOxide --> 0.1 FeOxide
The CrOxide removes some roughness left by the 8K Norton. I've found it to be useful.
I agree with everyone else -- I haven't achieved a straight-razor edge that matches a Feather DE blade.
.. Charles