How to properly paint dielectric material above metal?

[dchanini]

I want to paint oil above some parts of this model, but if i paint with the oil set to ''non metal'' it will have some white spots and i can't control the opacity of the layer, if i turn off the metallic properties of the layer it will looks better, but will be way too diffrente above a dialectric material.

So, how is the right way to do that?, i guess that this is kind of the same problem if painting other liquids too?

The difference btw them above the metal.
https://imgur.com/a/nURg9Yl

The difference btw them above metal and dielectric
https://imgur.com/a/JmnAMaY

[Jeremie Noguer]

This is a typical issue with metal/roughness shaders. You can either "cheat" and set your oil stains as metallic or use a specular/glossiness workflow, but depending on your target renderer you may not have a choice.

[dchanini]

This is a typical issue with metal/roughness shaders. You can either "cheat" and set your oil stains as metallic or use a specular/glossiness workflow, but depending on your target renderer you may not have a choice.

Ok, thank you!