What leaves a mark stain when touched that is initially invisible?I am doing an art project where I would like to connotate the sucking/absorption of something from a person when they touch something. I have tried litmus paper, thermochromic crystals, mimosa pudica sensitive plant, and they are all not quite right. It would be nice if the result from the touch left a pretty or eerie mark. But I would be happy with a wierd sucking sensation on the toucher. Any crazy ideas welcome! Thanks Rachel xxxx
The marks left by the oils on ones hands on a sheet of copper.
