I once was in a seminar by the CEO of an inkjet technology start up company who was a director of an HP's inkjet printer R&D group. In the seminar a brief introduction of the inkjet technology was given. A very interesting technology related this thread was introduced. Basically it was about how to prevent ink from drying up from the print head nozzles. If the print head nozzles are filled with water then the print head is left esposed to air the water will vaporize and dry up in less than a minute. This would have been a show stopper issue to the inkjet printer technology if ink would dry up so fast. What was invented is an additive that forms a very thin layer of film on the surface of ink. This film layer can prevent the ink from drying up fast. If I remember correctly this is a patented technology by HP. 3rd party ink manufacturers use different additives to achieve basically the same thing. So there is no patent infringement involved.ghwellsjr said:Joseph, one other point I want to make clear if it isn't already clear: never leave a print head with ink in it exposed to the air for more than a couple minutes. This means if you remove a cartridge to refill it, make sure you get the whole process done quickly so that you can return the filled cartridge back to the print head within a couple minutes. If you can't do this, you should put some other cartridge in the print head so that ink doesn't dry out inside the print head.
This also means that if you're going to remove the print head from the printer to flush it or for any other reason, don't leave it exposed to air for any substantial length of time or you will surely have lots of clogged nozzles. Do whatever you're going to do as quickly as possible.
I believe it is really not an issue to expose the print head to air for a while. I have exposed my print heads over 30 minutes or even hours without any problems. I at one time had a small vial of ink exposed to air and left in my bathroom for at least two weeks. The ink did not dry up. I could not see any loss of ink from the vial.