General Magic Tricks

palimpsest
a manuscript or piece of writing material on which later writing has been superimposed on effaced earlier writing.
something reused or altered but still bearing visible traces of its earlier form.

Susanne and Mike have been adding texts to an A3 sheet of paper to see how the reflected like from the cycling LED bulb effects the reading of it.

Mike found and interesting project

http://www.pbs.org/wgbh/nova/physics/inside-archimedes-palimpsest.html

where researchers have been subjecting old vellum palimpsests to new research tools to recover devious posts (a bit like this online messaging board)

When we put the bulb behind the paper rather than in front of it – it becomes more of a lightbox type image – which looks slightly different. There will be a technical reason for this. We are also finding that the fluorescent pens are more effective with so many layers.