Color E INK often suffers from looking washed out. E INK technology fundamentally differs from the millions of colors an iPad ...

Although electronic paper that can display monochrome static ... create a sandwich of three films of oil, each dyed a different primary colour, to enable a single pixel to be tuned to any colour.

However, water comes from different sources ... Stomach acid turns universal indicator paper a strong red colour. This indicates a pH value of 0, the strongest value of acid.