I ask because I stumbled upon an old Tam O'Shanter and acquired it. it's my second stone. My other is a Coti. Sometimes I read that the Tam is of a lower grit than the Coti, and sometimes I read the opposite, so the decision to use my Coti SS is now complicated.

I'd love to lap the Tam and try it out, and if it's really a finishing stone (for use after my Coti) then I'll only use water, but various forum posts disagree about the Tam's role. For some it's used in the middle of a progression and for others at the end. One needs slurry and the other doesn't.

Have any advice?