Rooster..I'm thinking if you have "bark" on the horn (so far all of mine have no bark on them) you'd probably only want to use a white compound or as you suggest, nothing at all.
If you are doing barked horn, like I've seen on Doug Campbell's and Lin's knives, I think you shoudl think about getting one of those floppy wheels, or the very loose soft sewn ones, cause they definitely do not heat up as much, kind of like the belts that have the crisscross pattern in the grit?
I'm thinking the bark would grab the fire out of the compound and not let go of it, even with acetone.
I should have stated that up front.
One other option would be to use a dremel tool with the 1 inch soft white wheels on them, and just do the "high spots" and leave the bark areas alone.
I do all the finger grooves of my knives with 240, 400, then 800 grit belts that are slacked off the edge of my wheel, then I use the dremel with plenty of rouge to fully brighten to almost mirror the steel in the finger grooves.
I'm betting when I do a bark horn knife I will handle the high ground of the horn with the dremel to see how that does.