Lapping in valves

Ok, Ill check it out than, thanks everyone

Id like to know though still/also why there are various grits of lapping compound, only makes sense that the coarser the grit the faster its going to cut. I guess I need to look for very f^ valves or vale seats whilst doing this and should consider a coarser compound if needed?

There are alot of videos on U-tube that show steps.