The thing that attracts me in terms of gum bi chromate
printing is that it is archival. Take a Kodak print and Scotch Tape a
quarter on it and leave it in the sun for a week. Remove the coin and see
what has happened to the color. I had a gum print tested for being color
fast at a lab in Germany and the results were amazing. The accelerated
test indicated that the image lasted for about 800 years before the color showed
determination. For the craftsman doing this by hand is a real
accomplishment.