
The mixture I used was about 2 parts water to 1 part white vinegar then brought to a boil and simmered for an hour to hour and a half. The papers I pressed between two old tiles I found and some broken concrete I used to weight them down with. Bricks work good too.
Occasionally, during the boil I would press the concrete to get more bubbles out of the paper. Softer less waxy leaves and greenery seem to print the best and the flower colors will change depending on their chemical reactions in the bath. So trying a variety of elements is a good idea. Also I used 90 pound watercolor paper and drawing paper for these prints but experimenting with papers is fun as well.
Hope this helps some and I can't wait to see more beautiful prints from other people too!
I will be posting some printed origami boxes and menko envelopes to my etsy page if you're interested at andyshouse.etsy.com.
Thanks so much!
Andy