Am currently painting an Immolator which features a rounded, clear plastic windshield infront of the gunner. Every picture featured in the WH Codex shows the raised detail on the windshield painted. Well, I can't make the damn paint stick. . .it just bubbles up. I tried scrubbing the thing with warm, soapy water, and still nothing.:((
Help?

You need to prime it first

The reason your paints won't stick is that the area is too smooth. You will need to give the paint someting to stick to. If you don't want the whole area painted then put blue tac where ever you don't want the paint to go.

Spray on some primer and then remove the blue tac. You will find you can now paint the areas you want.

u can also try PVA mixed with ink to get the glassy feel. just make sure you water it down.