Thank you Vlado 
No, they didn’t, but during their RnD phase they realised they had to decouple the RGB values to reproduce the fringing seen in anisotropic brushed metal.
Yes, they did experiment with acquiring sampled BRDF’s but ended up using a modified Cook-Torrence model due to the complexity of the sampled data and trouble reproducing realism in different lighting environments.
"But Snow explains that while a BRDF scanner is quite good for many surfaces it does not scan any anisotropic surface well as the result is so directional: “If you look at the small little round rivets on the suit that had concentric brushed circles, and you get these little bow-tie looking reflections from them”. ILM learnt quite a lot about the anisotopic surfaces were doing and created an anisotropic specular function for the silver suit in particular. “So we added a function that would change the behavior of the highlight depending on the direction of the brushed direction on that part of the suit.”
Snow does not feel that they totally nailed the anisotropic materials. “But that wasn’t the only problem, even though the metals were looking good, and Iron Man holds up really well and one or two of the shots I couldn’t tell later which bits of the suit we’d done – he was inside, then he was flying outside – he was in a range of lighting set ups and even though we set Iron Man up in a standard sand box environment, we were having to retool and tweek his material for each different lighting setup we were having to put him in.”