Why does cyanotype work?

I've been teaching a high school chemistry class using the cyanotype
process as our point for understanding chemical reactions.

We've looked at the iron II and iron III states...

We've talked about how potassium is the marker element for iron...

I'm looking for a way to explain the photo-reactive properties of the
process. I assume that the image formation is the result of a chemical
reaction. (Am I right?) What does light do in this process? How?

Is this a simple oxidation process? If we left a piece of treated paper
in the dark would it eventually turn blue also? Why does it leave an image?

Thanks,
Barry
Received on Tue Apr 4 07:08:24 2006