i am curious about the Toshiba : Press Releases 2 December, 2003
how the ink and the machine function.

1) It appears to be simply a thermo-labile toner in a modified laser printer.
2) The term"leuco," meaning white or colorless, is usually used to refer to the reduced form of the dye, as I mentioned with respect to methylene blue. However, it is not necessarily the reduced form.
3) As a wild guess, look up formazan chemistry. That group of compounds is unusual, almost unique, in that the leuco form is the more oxidized form.
4) The details are probably closely guarded by Toshiba. That process has had no impact in the USA. Bulk reprocessing of used paper is probably more cost effective and certainly much more secure than reprocessing single sheets, from which latent images might be recovered.
5) You might also be interested in the chemistry of Crayola magical markers that are invisible until developed.

Still, why are you interested in this arcane subject?

John

Thanks so much for the information.
I'm curious about how the machine and the dye works, but cant locate any manual on it.

1) Basic details of mechanism, particularly the chemistry, are not likely to be in any manual.
2) Maybe the machine was a commercial flop for the reasons I mentioned.
3) If you are interested in that particular area of chemistry, follow the leads I gave you.

John

I suggest a Ink Eraser/ Eraser

thanks!just come across this inkless technology:
Zero-ink printing revolution brings us the first pocket-sized full colour printer