Intermittent Banding When Bidirectional Printing Enabled

[costadinos]

I'm using a P50 with pigment inks, and I'm having this problem: whenever I have "high speed printing" (bidirectional printing) enabled, I get banding after about 10 consecutive prints. If I run a nozzle check right after it happens there are always some nozzles not firing (never the same, seems to be arbitrary).
When disabled I can print tens or hundreds of prints one after the other with no problems.

I used to think that this happened because pigments were more viscous than dyes (for which the P50 was designed for) and the high speed printing wouldn't allow enough time for the ink to flow properly. Can anybody confirm that this is the case, or suggest what may be going wrong?

 

[mikling]

Using a CISS?

 

[costadinos]

Using a CISS?

Sorry, forgot to mention that, yes, I'm using a CISS bought from CityInk (the feed tubes are on the bottom of the tanks if that matters).

 

[The Hat]

I would suggest you dump your CISS bottles as quickly as you can and get proper CISS bottles,
the ones with the tubing coming out of the top.

Your current (Marriot) CISS bottle setup is designed for use with dye ink only
and is not suitable for pigment ink, it’s only a matter of time if it hasn’t already happened
before the tubing clogs up with solid ink, rendering the whole CISS useless.

Your only other alternative is to switch to using dye instead of pigment ink
that way the CISS system will work far easier and more reliable for you..

 

[mikling]

Hat is onto the reason. Constant pressure ? Isobaric? baloney actually not needed for Epsons.
You need to convert to a drop tube system to run pigment reliably. Use normal containers and have the tubes hang and drop into the ink bottles. Heavier pigmented/darker colors will usually have more sediments. This is always an issue with pigment. Epson uses steel balls in their carts that used to move and Canon uses flappers to stir things up.
Empty the tanks. Pull off the tubes. Seal the bottom up or use old bottles and drill holes into the caps.

 

[costadinos]

Hat is onto the reason. Constant pressure ? Isobaric? baloney actually not needed for Epsons.
You need to convert to a drop tube system to run pigment reliably. Use normal containers and have the tubes hang and drop into the ink bottles. Heavier pigmented/darker colors will usually have more sediments. This is always an issue with pigment. ]

So, can the CIS systems with bottom tubes cause the problem I described (banding)? Whatever is going on, the problem always resolves, either by itself (if I leave the printer sit for an hour or so) or after a cleaning cycle. If there was sediment clogging the tubes, shouldn't the flow stop completely?

 

[The Hat]

If there was sediment clogging the tubes, shouldn't the flow stop completely?

The longer you use it the more chance you have of a total blockage,
it hasn’t happened to you yet but it will, besides you’ll keep getting poor print results.

Mikling just put it into nicer words and pictures for you to understand better than I did..

 

[Smile]

Well, you can clean it once more as it is not clean yet. You can also read another article on L800 printer that is built on the same base as your printer.

 

[mikling]

It appears that as you use it, you begin to block it up as the flow rate increases. It is like a clogged drain. If you run a lot of water through it, it will stop. If you trickle water through it, it will slowly get through with no problems.

These CISS systems as Hat described are nice cheap and convenient for dye ink. You can fill it, plug it up and ship it. It is not as easy on a drop tube. The trouble is vendors convince everyone that Isobaric is more important. Well, I won't fight the current. I am a solitary voice..plus Hat. But remember you've been warned. Pigment has sedimentation at some level. Some less than others. You have to deal with it on a logical practical basis.

 

[Smile]

@mikling
Nice pictures, how long are tubes inserted into the bottles, how much space to leave from bottles bottom?