thank you very much! i increased the sample value to 50 in the irradiance map menu and everything is fine now, i left all the settings on my usual values so the render time is still fast, with the 0/2 IM rate or the 3000 subdivs in LC the render time was too long

I think if you were trying to create that optical banding-effect of the material, you'd need to get creative with a procedural and fresnel effects. As far as just the sheeting, I think the previous posts have got it right, and you could also consider a bump or displacement map.