Seeing as no-one has answered in a week, I will reveal the answer
Barrichello’s 2007 helmet was covered with a thermochromic paint which reacted to heat. When Rubens’ helmet was cold it appeared to be completely black:
As it heated up, the black began to fade revealing Rubens’ traditional design
Once it got hot enough, the black was completely gone
Anybody can take the next one as no-one answered!