Permatex80038 Prussian Blue Fitting Compound, 0.75 fl oz Tube, Package may vary

This worked well for what I needed to see, which was the engagement of a starter motor pinion with the ring gear on the flywheel. The blue colorant did clearly show what I needed to see.

I Used it to level exhaust manifolds, apply with a paint brush to a sheet of glass and the high spots really stand out.Way better than trying to make it yourself and a little go's a long way. And you can use it on gears and bearings to check your shims. So I'll get a lot of future use out of it

Works Good !

It is Prussian Blue marking ink. It is blue and it marks.

This is not as visible as the paste some differential install kits come with but It does the job

For inletting metal to woodthis product is less messy than using lampblack

I bought this for use with my machinists granite plate while checking the flatness of various tools in my shop that need to be really flat. This was a fair bit cheaper than what is labeled as the 'proper' stuff yet seems to do the same job. I use a rubber brayer to roll out a small amount onto my granite plate and then transfer the ink to the high spots on any given tool to know where the high spots are. One example is when assessing the flatness of an old cast-iron hand plane that I might buy at a flea market. This could be messy if mis-handled but seems easy to clean up with a little mineral spirits on a paper towel.

a litlle bit goes a long way and lasts for days