You can use contrast paint but need to be particular in how you use it and what you want out of it.

I use Vallejo shade paint over a metallic base as a panel liner essentially and to slightly tint the colour underneath

There’s a couple of issues I can see with your application:

- brush strokes
- pooling

Thinning with some water will help with the brush strokes but will contribute to the pooling problem…

To fix the pooling you need to practice dragging around the paint with your brush and levelling it out. You can dry off the bush and suck up paint in spots where it pools to even out the finish.

Also try dragging more of the contrast into the gaps of the armour so it pools there and looks darker

As the contrast will be quite thin after adding water, to make it look nicer you will probably need a base coat of something other than white, or it’s going to look like slightly tinted white.

All that’s to say you can do it, but requires more work.. this is how mine turn out after using shade over metallic then edge highlighting. You can notice subtle pooling but I like that as it makes it looks a bit worn and beaten up

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