I'm trying to lap my valves so I picked up the lap tool, course and fine compound and both the Prussian blue and D ykem blue. After using them they both look like they do the same job except the Prussian blue doesn't dry. There's not much info online about using them.

 

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I would use the (D)ykem for this, you just want to mark the areas that make contact and wipe the marks off with said contact. Also, I'm guessing that's a robot editing your title? lol.