I've been creating a few routines recently that involve having a signed card change colour on the back. The first of which is shown
here which I'm quite pleased with. The most recent effect has the signed card appear in the coin compartment of my wallet folded up, which I'm most proud of.
As I state in the link my patter and presentation tends to go down the toilet when a camera is involved rather than people. But even with people I still haven't got a good justification for why the card should change colour. Of course the fact that it does change is enough to blow the spectators away, but does anyone have a good presentation which would justify the colour change? Or is it enough that it changes so unexpectedly to make it a good climax to the trick?
If it helps with theming for any ideas I am normally using blue and red cards for this (colours changing either way) but I have plenty of other colours available including black, green, ghost (I know red ghost pips are different but black pips are exactly the same as regular bikes) and will hopefully soon have some with completely different designs than the regular bicycles I'm used to.
Any help would be greatly appreciated. I'm normally pretty good at routining tricks like this once I've got an effect I wish to accomplish but coming up with good patter/presentation is where I start to falter.