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----- Original Message ----- From: "Ralph O Brown" <email@example.com> To: <firstname.lastname@example.org> Sent: Wednesday, January 19, 2000 11:31 AM Subject: Removing the foam Was: ANOTHER New approach to Refilling > I tried this sort of thing a while ago, removing part of the foam and using an > open top for filling on an Epson 1200 color cartridge. Apparently the foam is > there to hold the ink against gravity via surface tension and viscosity, which I > believe is related to why it fills with ink froth as the ink drains. I tried > cutting off about the top quarter of the foam and filling the cartridge to its > top, so there was a space with ink but no foam at the top of the cartridge. > What happened was the ink simply dripped out until it reached the top of the > foam and then stopped. My conclusion was that the foam is essential for this > type of cartridge to work. HP found a way around the sponge problem several years ago. Their cartridges contain a bladder glued to a flat spring such that the spring tries to keep the bladder flat and empty. The interior of the bladder vents to the outside. There is also a vent hole on the bottom of the cartridge with a ball valve to only let air into the cartridge. The bladder and spring ensure a slightly less than ambient pressure in the cartridge. The bladder inflates and deflates in response to changes in ambient air pressure in order to keep the ink inside the cartridge when not in use. When used the ink exiting the cartridge reduces the pressure inside the cartridge causing the bladder to inflate slightly. Eventually the bladder inflates enough that the ball valve at the bottom of the cartridge opens letting a little air into the cartridge. This method controls the ink very well and eliminates the sponge. Its a lot more complicated but does allow more ink in the cartridges. I wonder why Epson doesn't adopt a similar design? Perhaps they can't get around HP's patents. It is more difficult to refill than the sponge filled cartridges. To refill it one must block the ink nozzles (HP has the nozzles on the cartridge) and the bottom air vent. Then fill it with ink. Then inflate the bladder and keep pressure in it. Then seal the ink fill hole. Then let the bladder return to ambient pressure. Then unseal the air vent hole and the nozzles. - Please turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for instructions.
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