Thx a lot guys!
I'll try your suggestions!
I tried once with some regular black spray can paint as a sealer once. Then the chrome effect disapeared and it looked like regular silver. So it seems like you need to use water based color as backing.
In a way it's tempting to simply go back to using silver
So sanding or using stone wool like we did in the old days would help the chrome to stick better to the shell?