Sunday, 26 October 2008

Turning off my Epson 4800 printer for a month or more…

If you have read many of my posts in this blog you will realise that I have had lots of problems with nozzle clogging on my Epson 4800. Recently I realised that I was not going to be able to pursue my normal strategy to reduce nozzle clogging for a month or more, so I decided to try a different one based on my recent observations and experience. This post is about what I did and what happened.

To keep my 4800 happy and readily available for printing I normally follow a strategy of using Harvey Head Cleaner to print a nozzle check daily, along with printing a full spectrum print every three days through MIS Autoprint and keeping the printer humid by using a sponge full of water in the paper tray and a printer cover to keep the humidity in.

Recently, however, I have found that while this works very well the automated “something or other” (this posting gives more about my thoughts on this) that the printer does about once a week is quite likely to knock out various colour channels and that there is nothing I can do to stop it. Turning off all the auto nozzle checks and cleaning options has no effect. Some people have called this a “priming” function – but whatever it is it seems to do more harm than good and uses up a lot of ink.

About 6 weeks ago I realised that I was not going to be able to use the printer much at all nor be able to service the normal anti-clogging routine. So what to do?

I have become convinced that the key to a happy printer is humidity and avoiding the priming (or “something or other”) routines if possible. So I decided to turn off the printer and molly coddle it in a different way.

This I what I did:
  • I filled the sponge in the paper tray with water
  • I did a puddle soak to make the print head as humid as possible
  • I put in an additional water pot inside the printer cover as near the print head as possible
  • I wrapped the printer cover as tightly as possible to keep the humidity in
  • I reset all the Oregon weather station's humidity max & min readings - I use this to monitor the humidity inside the printer
Before bedding the printer down it was running perfectly with a perfect nozzle check.

I left the printer like this for a bit over a month (my records say it was 37 days). During that time I did nothing more than to refill the water sponges and about mid way through I set up another puddle soak.

Last Saturday I needed to do a biggish batch of printing so I woke it up.

How was it?
When I turned it on it did its “auto something or other” (which used 9.5ml of ink) before running the nozzle check I requested. Of the eight ink channels 5 were still perfect and the Light Black, Light Magenta and Light Cyan were completely missing – I can’t say I was surprised.

I ran a single nozzle clean and all three came back perfectly. The nozzle clean used 4.6ml on ink. I was pretty happy and relieved with this result!

So after 37 days of no use one single low intensity nozzle cleaning cycle restored the printer to a perfect nozzle check.

During that time the humidity inside the printer was mostly in the range 50-55% and according to the Oregon weather station the minimum in that time was 46% and the maximum was 67%. The reading from the paper tray was 53% min & 72% max, and from the room itself the range was 39% min & 63% max.

So I am more convinced than ever that humidity is the key to a happy nozzle clog free printer.

These printers seem to run OK for 12 to 18 months and then start experiencing these problems. This makes some people say that humidity can not be an issue as why would it suddenly change?

I do not know, but I can make some informed speculations.

I suspect that it is all to do with contact or wetting angles (go here for some background to wetting and contact angles); essentially the ease with which a liquid wets the surface it is sitting on or in contact with. Because the main problem I (and many others) experience is sudden whole ink channel loss it implies that it is not really about clogging – more likely the ink simply separates from the print head, which could easily be caused if the wetting angle is humidity sensitive. This sudden ink channel loss could also be due to an air bubble in the line, but personally I have never seen one of them.

If, however, the ink no longer wetted the surface of the nozzles/print head any slight loss of pressure might cause it to detach from the nozzle/print head, which would cause all the nozzles for that specific ink channel to stop working all at the same time.

Why might this start happening after 12-18 months?

I can think of a couple of reasons:
    a) The capping station seal around the print head may deteriorate a bit causing the atmosphere inside the capping station to dry out. This might cause ink separation if it is humidity critical.

    b) There may be a coating on the print head that reduces the wetting angle. If that wears due to ink flow going through the head, or due to any other form of use, then the coating might simply stop working causing the wetting angle to increase; making the whole system sensitive to low humidity.

One final thought: All of this is obviously quite challenging if you live/work in a desert…