Using the first recipe from this www.alternativephotography.com page I made a salt print of the kids participating in the HPS Explore Photography Workshop… http://www.alternativephotography.com/wp/processes/saltprints/a-dash-of-salt
The salt print took 40 minutes to expose starting in the early morning fog. The image was probably a little too dark in the end, but a great start none the less.
The salt print process was used by Henry Fox Talbot, one of the first people to invent a photographic process. Here is more information about Talbot… http://www.metmuseum.org/toah/hd/tlbt/hd_tlbt.htm