Waders,

I created a little demo for an effect you might find useful.

Using the mouse or your finger, you "brush" dust off to see the text of a book.

It is on my site www.ashatej.com

Scroll to the bottom, it is in the demos section (the only one).

There is also a link to download the sources in a zip if you so desire.

It should be pretty easy to follow what's going on.

The images I used are all CC0, so feel free to do with it what you like.

cheers,

Shri