why is my heat shield turning brown?

[blackvalkyrie]

my heat shield on the right side of my 97 standard is light blue at the tip and the rest of it is starting to brown...any one know why? ???

[Otus]

Just guessing, but when tempering steel you get a rainbow of colors from different temperatures of the steel a wheat color as what you want for a knife edge. So what I'm thinking is that your shields are hitting different temps in different areas.