I wasn't expecting anything from dampness, it was just a bonus element.
The main point was the pressure. I have seen black inks transfer from pressure over 100 years after printing. Black T206 backs seem to transfer more readily than others, with red being the second most common. So since I wanted to see if it would transfer after 100 years I figured the beater nobody wanted to trade for was a good experiment. I'll probably look for a beater tolstoi or old mill to try, and pick up a couple metal plates so the cards are less wrecked by the experiment. Other good candidates would be cards with back damage and/or creases from being removed from a scrapbook. Using those would eliminate the dirt from the equation.
While it was a serious experiment I'm happy we could have some fun with my poor phrasing of the alcohol element of the next step.
Steve B