• Pigment ink & CIS systems

    This article is being written up as the topic of using Pigment ink in Continuous Ink Systems (CIS/CISs) is one that repeats fairly regularly and it’d be nice to have this as an FAQ, of sorts.

    A Bit of History to CIS systems

    If you’re not interested in the background to CIS systems and pigment ink you can skip ahead to the Pro-active and Re-active measures you can take to avoid or resolve related issues

    The first thing to note is that in the very early days of CIS systems there was really only one available which was developed by the company that was MIS Associates in the USA (inksupply.com). The company has since been sold on and bears little resemblance to the old entity but their system was based around a simple dip tube reservoir where ink would be pulled into the cartridge block via the ribbon tubes and then fed into the printer.

    Most early Epsons were dye ink printers so this didn’t present a problem, but with the advent of the C/D series printers and models like the Photo 2100/2200 and R800, the pigment inks started to make inroads and with it CIS adoption.

    It wasn’t long before clone CIS systems made from moulded plastic appeared and the key design difference with these was the way the ink was drawn directly through a hole in the base of the reservoirs.

    What was common to both the clone and the original MIS designs was the use of full cartridges to feed the printhead ink intakes. The use of these full capacity cartridges ensured that any pressure differences experience as tube flex, environmental changes, etc… could be evened out and of course provided a full head of ink above the printhead so it would continue to feed properly.

    Unfortunately, it also meant that any solutions that had a component that might settle or concentrate towards the base of the reservoir/cartridge (ie: Pigment ink) had a much easier time of building up in the cartridge, particularly after long periods of non-use.

    Concentrations of ink…

    This is different from a standard cartridge (refilled, refillable or original) as the pigment concentration in individual cartridges is limited to just one cartridge volume of ink, so while you may initially hit a bit of a “clog” the lighter concentration eventually takes hold and clears things.

    The reason a CIS system exacerbates the issue is that you have anywhere up to 12 times the amount of ink in a single container. So ink concentrations towards the base of the reservoir are considerably higher and made up of those multiple cartridge volumes. When you add in the factor that this then feeds the pigment rich solution into the cartridge where it can further build up, you end up with a sort of perfect storm of clog promoting solution.

    Even if you remember to agitate/mix the ink in the reservoirs on a regular basis it’s not possible to clear out the cartridges themselves (if they’ve gotten concentrated ink in them) without manual intervention. More on the latter further down.

    Now the advent of the Ink Republic CIS systems provided the use of a “buffer” rather than a full cartridge capacity system so the concentration of ink in the cartridge/buffer is much reduced and the use of individual ink bottles does make things easier to mix back into solution again rather than the single, multi-compartment moulded reservoir block.

     

    Pro-active measures

    Mixing (before printing and/or before turning printer on)

    One of the simplest ways to reduce ink clogging from the outset is to regularly agitate/mix the inks in the reservoirs but most important of all, is to do so before the printer is switched on, particularly if the printer has been unused for reasonably long periods of time.

    This ensures that any concentration build up has been removed into an equalised solution, and the usual re-priming routine won’t pull overly concentrated ink into the cartridge/printer.

    Regular Exercise (Printer use)

    Coupled with “mixing”, the use of regular printing to exercise the printhead nozzles helps to ensure that concentrations of pigment don’t build up in the cartridges themselves. It’s somewhat counter intuitive but it’s actually more cost effective to print more than normal that it is to hold off and have to run numerous printhead cleaning routines to clear clogging.

    Swapping Reservoirs to Dip-Tube/Individual bottles

    This process is a bit more involved but basically means switching to a suitable bottle for each ink and a dip tube that reaches down to stop roughly 1cm before it comes into the contact with the bottom.

    This approach allows the inclusion of things like individual tube clamps (helps with maintenance), better ink mixing, and also draws the ink out of the bottle much higher up, so it’s less concentrated.

    That said, it’s pretty drastic and something only for those who really prefer the dip-tube approach to integrated blocks.

    Maintain Humidity

    Because Inkjet ink is a water based fluid it’s just as vulnerable as any other liquid in dry, hot conditions. Such environments draw moisture out of the ink and promote clogging, particularly in the printhead.

    Use of a printer cover can help reduce drying out but a further trick to consider (but only with careful consideration!) is to do the following:

    1. Shutdown the printer and remove the power cable.
    2. Place a small, stable-base container of water inside the printer (locate somewhere on the platen area the printhead usually passes over) with a small amount of room temp’ water inside it.
    3. Close the printer cover and wrap the power cable in a note to “remind yourself to remove water container before plugging the printer back in”.
    4. Cover printer if possible and leave.

    The premise behind this idea is that it maintains a humid environment that is unlikely to dry out the ink in the nozzles. Use entirely at your own risk however.

     

    Reactive Measures

    If the CIS system, has become particularly prone to clogging there’s a few things that should help you get out of trouble:

    Refreshing The CIS Loop

    Before you go with replacing your ink though, you can refresh the ink held in each of your cartridge and tubing as follows:

    Equipment needed:

    Process:

    1. Ensure the reservoir ink has been thoroughly mixed.
    2. Plug vent holes on all reservoirs or individually clamp tubes (eg: InkRepublic kit).
    3. Unplug/unclamp specific/target ink reservoir/tube.
    4. Shake target cartridge to mix up ink inside.
    5. Attach connector to syringe and insert into cartridge outlet/exit-port and hold cartridge upright (as if installed in printer).
    6. Gently draw 30ml+ of ink out through cartridge outlet.
    7. Check which reservoir ink is from before emptying syringe into the target reservoir.
    8. Repeat steps 6-7 once more with same cartridge & reservoir to thoroughly refresh ink in cartridge.
    9. Re-plug/clamp target ink reservoir/tube.
    10. Flush our syringe and adapter then repeat steps 3 – 9 for the next ink.

     

    The purpose of this routine is to flush out the contents of the cartridge and replace it all with thoroughly mixed ink solution so you can then use the pro-active process to avoid problems in future.

     

    Ink Age/Replacement

    All inks have a shelf life with factors such as inhibitors failing to block algae growth, or chemical breakdown causing more problems then fresh ink would.

    Keeping a clear idea of how old your ink is, by marking its purchase date, will obviously help but replacement is a last ditch thing if the ink is less than 18 months old. Two to three years might be pushing the lifespan and be time to buy a new supply.

    The pull-through-adapter tool (used in the CIS loop refresh, above) is also useful for removing old ink that needs to be replaced. Granted you could purchase a new CIS system but assuming you want to keep it you can flush things out as follows:

    Equipment needed:

    Process:

    1. Thoroughly mix up remaining ink in the reservoirs
    2. Attach syringe to adapter to the exit/outlet port on cartridge
    3. Hold cartridge upright (as if installed in printer)
    4. Gently pull through all remaining ink, dumping from syringe as necessary, into a waste bottle
    5. Check all possible ink has been removed from target cartridge/reservoir/loop
    6. Partially fill reservoir with approximately 5 – 10ml of new ink supply (this will be wasted)
    7. Mix around in reservoir to mix/combine with old ink as much as possible.
    8. Re-insert syringe/adapter and pull new/old ink mix through system and empty as much as possible.
    9. Dump/Dispose of this ink (Do not re-use as it will just contaminate your new supply)
    10. Flush syringe and adapter to clean thoroughly.
    11. Fill target reservoir with new ink
    12. Gently pull through new ink into cartridge to re-prime.
    13. Ensure no air remains in cartridge outlet.
    14. Empty new ink in syringe back into target reservoir
    15. Plug target reservoir and mark as completed (to avoid re-doing by mistake!)
    16. Flush out syringe and adapter
    17. Repeat for the next colour/reservoir

    .. and that’s about it.

     

    Summary..

    So, to summarise a couple of key things. Pigment inks in CIS systems can lead to more problems than Dye inks but in most cases the issues can be side-stepped, delayed or at least resolved with some maintenance and a bit of care.

    Buffer systems like Ink Republic CIS systems have an edge for pigment inks but do come with some disadvantages such as lack of support for some printers/chipsets.

    Hope this article has provided some useful tips… Feedback, improvements, welcome.

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