Do a drawing so that the lines of the drawing pick up the purple. Then remove the purple sheet, and turn the paper over to the side where the purple lines of the drawing show...and color some of the areas with brightly colored wax crayons.
Then quickly run it under water...or dip in a pan of water and lift. The purple will run over the part that has not crayon...and the crayon part will resist the purple.
Experiment with it.
Another thing we did...was to do the drawing...and then the students controlled the amount of purple wash with water and a brush.
Does anyone remember those mimeograph sheets - the ones that made purple copies and had to be run through the machine by hand? Well, our secretary was doing some major cleaning and brought down boxes of this stuff. Any ideas on an art project with them? We don't have the machine anymore (and haven't in the 9 years I've been there!)
K-12 Kansas Art Teacher