I did read that inkjet printers need to regularly clean their cartridges so that their tip don't dry. The common recommendation therefore is to not remove the power supply, which I'm not doing. What I'm missing in common recommendations is the distinction between removing power supply and switching the device off. For instance, in this answer the user says

I suggest to not unplug the printer's power cable. Most devices will do a self-test, wasting lots of ink, when the power was interrupted. The cost of the power consumption in stand-by mode, is nothing compared to the cost of the ink that's wasted during avoidable self-tests.

I do own a HP OfficeJet and wonder whether these printers (and generally other inkjet printers aswell, if this is generally applyable) can safely be shut off (power is still connected). Does the printer still automatically wake up and clean its cartridges? I have never seen my printer wake up automatically to clean itself after I switched it off. In other words, will the cartridges be damaged by shutting the printer off by drying out, instead of just letting it go into automatic standby?

  • I cannot give a definitive answer, but I have never noticed a Canon or Epson inkjet printer wake up for cleaning either. In all the printers I have repaired (not very many), when the printer is switched off it moves the printhead over a foam pad and puts a cap with a silicone seal over the nozzles to stop them from drying out. Mar 26 '16 at 15:14
  • I'm not aware, either, of any inkjet printer that does any form of self-initiated cleaning while in standby. There's no difference in standby vs. powered off in terms of ink drying in the nozzles. Powering on does entail a self-test and nozzle cleaning, which uses a lot of ink. If you're using the printer periodically (say at least every few weeks), standby will save you some ink. If it's idle for longer than that, the power-on cleaning will be good for it (if it's sufficient). Maybe better is to leave it in standby and print a page every few weeks.
    – fixer1234
    Mar 26 '16 at 17:06
  • No matter how you use them, inkjet printers are a waste of ink. Every power cycle and automatic head cleaning wastes ink. If you don't use them often enough, integrated nozzle cartridges need early replacement, wasting ink and separate head systems require replacing the whole printer, wasting ink. Leaving the unit in standby only wastes ink if the system goes through a power cycle, though any heat created by parasitic power usage will keep the unit warm and probably help dry ink in the nozzles. With inkjet printers, you just can't win. Learned over the years using them for print proofing. Mar 26 '16 at 19:07
  • @Andrew on amazon.de, a comment says "Der Drucker reinigt sich regelmäßig selber. ".. for the rest of the world: "The printer regularly cleans itself.", which I thought means it will waste some ink itself when it deems useful. Mar 27 '16 at 12:50

I don't think it makes a big difference—the printer caps the printhead when not in use to prevent it from drying out regardless of whether it is on or off. What matters is that you avoid cutting power to the printer, especially while it is busy—this could leave the printhead in an uncapped state which will more often than not lead to printhead clogging and (in severe cases) possibly failure. (Trust me, I learned this the hard way with Epson printers 😦. Unlike HP printers, Epson printers tend to treat carriage jams as fatal errors, typically with error codes 0xEA or 0xE8, which require a power cycle to recover from. This results in the printhead becoming uncapped for an extended period of time, causing severe clogging.)

For printers that are not being used regularly, I'd generally recommend that the printer be power-cycled every week or so (though this can be longer for HP printers, up to several weeks at a time) as doing this typically triggers a maintenance cycle that helps keep the nozzles clear. This process does consume some ink, and because of this need for maintenance (which HP calls servicing), inkjet printers are generally best for regular printing. (HP printers are better than most over long periods of non-printing; see this Wirth Consulting study for details.)

Printers generally do not turn themselves on for servicing. The HP PageWide printers do service themselves when powered on and idle; see the PageWide Technology whitepaper for more information.

This HP article on how ink is used contains relevant information on ink usage in printhead servicing.

  • Out of curiosity, I've disassembled several printers before discarding. The servicing cycle uses a shocking amount of ink over the printer's lifetime. The manufacturer didn't make much difference. Mar 26 '16 at 19:16
  • Indeed, if an inkjet is rarely used, the cleaning cycles may use more ink than the printing.
    – hdhondt
    Mar 26 '16 at 23:27
  • @hdhondt: Yup. That's why HP has "economy" cartridges for users with less frequent printing needs. They contain marginally less ink than normal cartridges and come in cheaper packaging, with a cost per page that is a tiny bit lower than the normal standard-yield cartridges in normal retail packaging.
    – bwDraco
    Mar 26 '16 at 23:29

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