Hidden wootz

[archer]

Lately I've been learning about etching with ferric chloride. The puzzle comes when you've used a light etch and don't see anything but a frosted look with your eyes. When the camera see's wootz. The latest CSI Miami had a bit about a fingerprints' acid doing a mild etch, not seen by the human eye on brass.
They enhanced it magnetically. Here's a couple of examples. The frosted is seen by eye. The other shows the camera seeing wootz? to the right and damascus on the left where blade was scarfed. Ok, have I lost it or does this make sense?

Steve