Does using a re-manufactured compatible ink cartridge void my warranty?

According to Hewlett-Packard the use of a re-filled cartridge does not affect the warranty unless failure or damage is attributable to it. As far as we are aware, this is typical of all manufacturers' warranties and we understand that the Office of Fair Trading has written to printer manufacturers making this clear. The ink does not touch any part of the printer or internal parts other than the cartridge and print head. The ink is applied to the paper as the paper is fed through the printer. We have never had a problem with our re-filled cartridges causing damage to a printer.