Today's guest site is the Colour Printing Forum http://www.colorprintingforum.com/inkjet-printer/silver-inkjet-ink-130.html

I don't think you'll find these commercially available (at retail level). I work in the print industry and metallic ink jet inks are the holy grail at the moment. They are available for printing small printed circuit boards (such as onto flexible plastic or paper backing) and, most importantly, for printing RFID antenna directly onto packaging.

These inks are horrendously expensive and would only be available in industrial quantities. One of the problems for 'public' use is that they contain metallic particles which would clog up a conventional print head almost immediately. Also, the pigments tend to settle out so you would end up with a clear cartridge with a silver sludge in the bottom! Conventional ink jet cartridges have dye based pigments which are dissolved in the medium. Industrial ink jet printers use a system where the inks are continuously circulated past the print head, under pressure. This is done to increase print speed but also keeps the inks agitated/mixed.

Fotonic do a range of metalic inks - not sure they are available here in the UK though.