RA69 I understand what you're saying, and I agree with Steerpike on the phrasing of the ink question, but on the topic of the colour change, I have to say, I took PCP's post as saying no colour changes either - he said "This is not a color change." Which essentially means the method is something other than a colour change. RA69, "This" can reasonably be expected to mean either the method or the effect - hence, "This effect is not a colour change" and from what I understand, neither of which are true. If the method is not a colour change, it stands to reason that there hence is no colour change... I can understand the difference in saying there is no heat-sensitive ink and no ink at all - but the difference between those two regarding the colour change is like saying "I did not stab him with a knife" where in reality I first shot him, and then stabbed him. Random analogy, first thing I thought of.