John in NM
Heatless? Might as well think there is perpetual motion

Best course for low heat is a friable burr, just like with a grinding wheel - high speed and friable.

If Cratex was recommended, I would bet its because they give an acceptable balance between cutting speed (fine though they are) and low heat due to their typical low speed use. They are an excellent product, though less aggressive than a typical hard stone bit. If your shape is formed and you just need to refine an edge, Cratex is a good thing to try. If you're going to shape a bevel, they will probably overheat it from having to linger too long to get the job done.

Disclaimer - I've mostly used Cratex wheels shaping and polishing non-ferrous metals like silver and brass. Just extending what I recall of their behavior to ferrous application.