The biggest concern is that you may not notice right away when the cartridge finally does give out, and printing with no ink can damage the expensive-to-fix print head.

Update: Tim Rosencrans adds: 'There are a couple of consequences to this procedure. To see if your printer uses microchip-based cartridges, check the ink level if clicking on the picture of the cartridge with the ink level shows the part number, manufacturer and type of cartridge, then the printer uses a chip).' Update: Michael Kincaid writes: 'This trick only works on Epson printers that don't use microchips on the cartridges to track the ink level (such as the 777, C60, C80, 1290, and many of the Photo models).

I was able to continue printing, and the output still looks good, so I'm getting more bang for my buck with this cartridge.'

When the ink holder moves into position, lift up the lid to the cartridge that is 'out' of ink, then close it without removing the cartridge.

Open the lid, hold down the ink button.

'I'm not entirely sure how this will affect the ability of the printer to track the amount of ink, and Epson recommends against inserting a used cartridge (although, technically, I didn't really remove the cartridge, I just tricked the printer into thinking I did). However, users should be aware that there may be unintended consequences to this approach. Although there is no standard way to work around this limitation, Jonathan Greenberg found a technique that seems to work for him with an Epson 740.

As we have noted before, Mac OS X's Epson print drivers tend to refuse to print when the ink level reaches a certain level, even if ink remains in the cartridge.

Epson nx420 ink levels