Need Help : Varnish And Paint

Hi Georges23,

I've not used an anti-corrosive varnish before, but without knowing more about the product I'd probably go down the route of making a test piece.

Get some old metal scraps, similar to the materials you've already coated, then coat them with the varnish, leave a good few days to fully cure, maybe add some heat cycles (replicate exhaust getting hot) if you feel that's necessary?

Then apply whatever coating you're wanting over the test pieces, leave them exposed, outside maybe for a few days and see how they've reacted, and again subject the newly coated test pieces to heat cycles if you feel it's necessary.

Inspect and physically test, try scratching to see if they fail easily or are resistant, that should test the bond between the two coatings.

Not sure if that's of use or if you have the time to try, but first thing that popped into my head. Good luck pal