Can anyone tell me the formula for photocopy toner in particular the one I am after is Xerox toner part number 6r90100 used in the 5090, 5390, 6135, 6180 and Docutech machines or... direct me to a site where I can find out to make toner.
Try your local university library. I forget the exact name of the reference series but it could be something like "Chemical Formulations" ... it has chemical formulas for all sorts of household products, specialty products, etc .. should be near the Chemical Abstracts in the library stacks...?
The product MSDS sheet will also be helpfull, although typically not releasing proprietary info (as it should be).