Stuarts Micrometer Marking Engineers Blue is a non-abrasive, easily spreadable marking paste. It contains a high concentration of pure Prussian Blue in a grease based paste. Used for locating and indicating high spots on metal surfaces, machine bearings, machine tool beds etc. It gives a clear, perfect mark on any metal, in any light and being a lubricant cannot damage bearings or other working parts. Apply sparingly, a little goes a very long way.
In addition, thinned with a little methylated spirit it becomes a Layout Fluid for use when scribing clear and precise lines.