Many thanks for the help on this. I’ve now finished the ~50 metre print run and I thought I’d share what I learned, lest it be of use to someone else.
So, turns out I bought my z3100 in 2007. I have used it in bursts, with long periods of idleness of sometimes as much as almost 2 years, but equally there have been short burst of heavy usage. When I’ve needed it for something, it has always been a very frustrating process, as I spend countless hours trying to 1/ get HP and Apple’s software updates to work together and 2/ get the print quality consistent. The printer has had 2 head changes over the years, both MK-R I think. I never print matt, but I also know that the MK ink is the bugbear of the printer, as I learned from HP engineers themselves. I feel kind of dumb about my use of the printer, because I was involved, in a small way, with the beta process, back around the launch of the z3200, the upside of which was being invited to Photokina by HP in 2008, where they had two very large prints of my pictures hanging on their stand, extolling the values of their new red inks. I was also fortunate to be invited a few years ago, to their facility in Barcelona, where they develop their printing solutions and where we were shown their Indigo solutions. What a great place/facility it is.
In Feb 2017, I replaced the MK-R head, as despite Mark’s help, I couldn’t get the existing head to print properly. Then 6 months later, after the printer had lain idle for around 4 months, I found that it was already not printing MK-R properly on the Diagnostic chart. There was a lot of gunk on the head and after some cleaning etc. It was printing ‘almost’ normally again. However, the Diagnostic chart still had quite a lot of missing lines on the diagonals of several colours. This I assumed was simply the age of the printer. Wrong.
This time last year, I once again had problems with the MK head, after another 4 or 5 months of little to no use. I had a large print job and just accepted to make the best I could out of it. *However* I also decided to follow Mark’s advice and just leave the z3100 turned on ALL the time. And so once again, after a full year with almost zero use, I come to a large print job, of around 45 metres of 24” paper. I started off with a Diagnostic chart and unsurprisingly, the MK block and diagonals were *empty*. Zero ink. There were also what HP docs suggest is an acceptable amount of missing diagonals and missing lines in the narrow vertical blocks, in some of the other colours. Also … and this is the *crucial* element, the R ink was pale. This is what has been causing me the most problems, as the colour is not consistent for a sustained period.
As I previously mentioned, I ran a number of head cleaning cycles on the MK and this seems to have resulted in a build up of purged ink, which then was being picked up by the head and causing some smears at the start of prints. Not every print … probably every 2nd or 3rd print. So I left the printer overnight and tried cleaning the resting/parking station in the morning. Oops. I didn’t take the side panel off, but moved the heads to the head-swaping position and could just seen in well enough to see that there was a large blob of gunk, at the far side of the sponges. I tried to stop the carriage by lifting the perspex lid when it was to the left, hoping I’d have enough time to clear the gunk away. This didn’t work as I hoped. It took a few attempts before I was confident about being able to get in with enough time, before the head came back, but then I discovered, that the sponges are not there when the printer is printing. Instead there’s a plastic tray, which is on a spring. I cleaned this anyway. There was a lot of wet ink on it. Bad news was that the printer now told me I had a paper jam. Following the instructions and 2 restarts failed to clear the message. Oh dear … then I noticed that the head wasn’t going fully into its rest station and in a moment of inspiration, I tried to move it and much to my surprise, it glided easily. I pushed it fully into its resting station and restarted once again. Bingo. All was well again. Phew. I then continued with the day’s printing and had zero problems of smeared ink, until very late on, at which point I decided to stop for the day. The next day, there were zero ink smears once again. So, my conclusion is that my cleaning was probably of no consequence whatsoever and it was simply the time I allowed for the inks to dry, or flatten out (gravity?) that solved the issue. I think it may have been caused in the first place by the extensive head-cleaning I had done. Subsequent to this, I’ve had another full day or printing, with no smear at all.
So … the results of this long print run are : a new addiction to Diagnostic charts, but other than that I’ve basically learned that if you print with these machines, then they will perform as intended, but sitting idle and turned off, is a killer. My Diagnostics have gone from serious problems with the MK-R and moderate to slight problems with others colours, to *absolutely perfect everywhere*. The last Diagnostic, under very close examination with a loupe, shows not a single break in any of the diagonals nor any lines in the narrow blocks to the left and the big blocks at the top, are all absolutely solid. How did I get to this point? Leaving the printer turned on and printing a lot. The question now is … as it enters another period of non use, will leaving it turned on all the time, mean that I can come back to it in 2 or 3 months time and it will print a perfect Diagnostic straight out? Time will tell … but my feeling is that yes, it will. At least I now know how to fix it. I’ll probably run a Diagnostic every month of non use and I’ll report back how it goes.
