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From: neff@hpvcfs1.HP.COM (Dave Neff)
Newsgroups: comp.sys.atari.st
Subject: Re: The ST, HP DeskJet, and "permanent" ink.
Message-ID: <2150005@hpvcfs1.HP.COM>
Date: 5 May 89 20:09:15 GMT
References: <890504.00521811.073114@SFA.CP6>
Organization: Hewlett Packard, Vancouver, WA
Lines: 74

My posting about refilling DeskJet ink cartridges was not intended to
discourage the practice.  Rather it was intended to make sure people
knew that a single cartridge could not be refilled indefinately.  I have
not heard if we have a official HP policy "against" refilling DeskJet ink
cartridges but it wouldn't surprise me if we actually might use this as
grounds to void a warantee.  Now I'm just an R&D engineer and we have
refilled pens in the past (initially due to pen unavailability when both
the DeskJet and the pen were being developed).  But it is possible for
some inks to mess up your service station.  I just want people to know
the risks and limitations of refills.  Let me explain two problems with
some inks.

1) "Crusting" occurs when ink slowly seeps out of the cartridge and dries
forming a sort of crystaline buildup.  These particles can fall in the
priming tube and clog it up, resulting in pen prime having no effect.
There are other negative side effects of crusting such as clogged up
ink jet orafices.

2). "Drooling" occurs when ink slowly seeps out of the cartridge but
does not dry, rather it drips.  These drips can fall in the priming tube
and clog it up, resulting in the same effect on pen priming.  There
are other problems with "drooling" messing up your service station area
(the wiper, cap, and other stuff on the right of the print carriage).

An ink can both drool and leave a residue which will subsequently crust.
There are other problems with some inks such as dry time and print quality
variability with paper type, but these problems are more or less self
evident when you try various inks.

The ink in the DeskJet cartridge is designed to overcome the drool and crust
problems.  Ink that you refill will likely have one or both of these
problems.  It is possible to take apart the service station, clean it,
and unclog the tube using a water filled syringe.  If you suspect 
your DeskJet is not priming (when the tube is clogged a prime will
run but no ink will be sucked out of the cartridge so no prime will
occur) it might be necessary to clean your service station and unclog
the tube.  Normal DeskJet users should NEVER have to do this, the
service station is usually a no-maintanance device.  But if you play with
various refilled inks you could run into this problem.

As for pricing of DeskJet cartridges our goal is to make the cost of
DeskJet cartridges comparable to the cost of laser printer toner
cartridges on a cost per page basis.  Comparing prices with ribbons
is not totally unreasonable, but ribbon print quality degrades with
time and it is difficult to say when the ribbon really is unacceptable.
Hence true cost per page numbers with ribons is not "fair".  With a DeskJet
each page will be as black as the previous until the cartridge is empty.
This is not the case with ribbons.  Now some people refill toner
cartridges to save money and that will invalidate the price per page
comparison between toner and ink cartridges.  Of course if you also
compare with refilled ink cartridges the numbers once again are different.

I hope this helps.  Personally, I'm just an engineer that did much of
the DeskJet+ firmware (especially relating to performance improvements)
and also worked on the Epson and Landscape cartridges.  I really don't
care if you refill pens or not.  I'm just trying to let people know the
risks involved.  To the best of my knowledge we have no official statement
saying "rifilling ink cartridges will void your waranttee" but I am sure
if we found out someone was doing this and when they brought their printer
in for some service station related repair we would say this repair
is not covered.  I am not turning you guys in of course :-).

Its up to you to trade off the risks and benefits of refilling cartridges.
I am just suggesting you take into consideration the risk of voiding
waranttee repairs and clogging your service station.  If your printer is out
of waranttee this risk/benefit analysis might be easier.  I am also
warning you that you will likely to run into problems related to priming
pens (a prime will have no effect).  Do with your printers and ink
cartridges as you like.  After all, you paid for them :-).

Happy printing ...

Dave Neff
hpvcfs1!neff