This is a part two article on print head life. The first is here.
The second most significant factor in shortened print head life (besides paper strikes) is severe intermittent use of the printer – or inactivity. Most users believe that if they barely use their printer it should last a lifetime. Unfortunately with pigment inks…the opposite is true.
All pigment ink settles out of suspension
Pigments are solid matter suspended in liquid. Eventually the pigment settles out of suspension. It does not fall all at once, but rather slowly. However, a sudden atmospheric change can shock pigment out of solution. With high-quality encapsulated pigment, it is very easy to gently shake and redistribute the pigment into suspension. With cheaper inks, shaking can sometimes aggravate the clumping together of pigment particles that have come out of suspension.
Pigment encapsulation prevents pigment particles from clumping together because it isolates the static charges that attract each other. Encapsulation is a thin micro-layer coating that insulates each pigment particle. As a familiar example, the hard candy coating of an M&M candy is an encapsulation of the soft chocolate inside. It may be hard to imagine it is possible to encapsulate pigment particles because they are so microscopically small. But, EPSON, HP, and Vermont PhotoInkjet have unique encapsulation technologies. It is highly unusual for a non-OEM company to have encapsulation technologies, but this is the performance advantage of ConeColor and Piezography ink formulations which have a reputation for being non-clogging.
While it is easier to see pigment settling in bottles of ink, it also happens in both small and large format cartridges. It can especially happen in CIS systems and in the ink lines of large format printers.
The Epson standard help file text on replacing cartridges is exactly: “When a cartridge is more than six months old, you may need to replace it if printouts don’t look their best. If the quality doesn’t improve after cleaning and aligning the print head, you can replace the cartridge even if you don’t see an ink message on the display.”
The Epson business model is to sell as much ink as possible. EPSON hopes that you use up all the ink quickly and buy more. But, it is not necessary to discard partially used cartridges because they are six months old. Discarding cartridges (even if not spent) avoids technical support issues surrounding nozzle gaps and micro-banding, and helps increase Epson ink revenues, but is hard on the environment and expensive for the end-user. Old ink can become a tech support nightmare. But, there are alternatives to letting pigment inks set in printers which are not used as frequently as expected (which is to use up the ink supply within 6 months).
Not everyone is as active an ink customer as Epson might wish. People get sick. They go on vacations. They get distracted. It is not uncommon for us to hear from customers who have left their printer set for a full year without use. Generally speaking, pigment ink allowed to sit in an unused EPSON large format printer will begin to settle out in the ink lines within just a couple months.
However, this same inactivity might cause the ink cartridges to push higher levels of pigment through the system. Ink in an EPSON cartridge is drawn from the middle of the cart as the bag that is holding the ink begins to collapse. If the cart was relatively full when the printer was shut down for a lengthy time, it is possible that the pigment will have settled towards the outlet. If the cart was more than half used, pigment will most likely have fallen below the outlet. As you can imagine, either case will also reveal color management issues, and in seven or six shaded Piezography ink sets image posterization occurs.
Because all refillable carts feed off the bottom of the cart, pigment settling is more of a concern to customers of refillable cartridges. The overload of pigment will prevent clean nozzle checks, not usually due to the pigment and the ink jets, but rather the viscosity of the ink as it moves through the ink lines and dampers. The ink jets piezo pumping action will not produce enough force for the ink to behave normally. Further, settled pigment in the ink lines will have already narrowed the passageway towards the dampers. Finally, the dampers themselves will begin to filter pigment because they are not designed to handle such huge amounts of pigment in a small volume of ink.
At this point, the customer usually thinks they need a new print head or that the ink has ruined their machine. Very few customers take responsibility for inactivity believing that using a printer too little actually preserves it. The opposite is true. Printers are designed for frequent use. The micro-physics of ink flow through the ink lines, dampers, micro channels of the print heads, and finally out the ink jets is a complex system that is dependent upon a carefully formulated ink. Allowing the ink to sit in a printer that remains inactive, changes the formulation’s fine balance. This is the same for EPSON ink as it is for ConeColor and Piezography ink.
And please do not misunderstand. We are not advocating for the use of old ink. Ink has a shelf life when un-opened. Once it is opened it must be used within that shelf-life and kept tightly sealed. Old ink will not print as will fresh ink. We are advocating for the use of ink beyond six months.
What you can do to prevent pigment settling
First, we recommend removing your carts and gently shaking them every few weeks. EPSON instructs the customer to shake the cart before inserting. Nearly all ink customers today are used to shaking their carts before first use although they may not clearly have known why. You can remove the carts to shake or gently rock the entire printer. If the printer is not going to be used weekly, then a power cleaning should be performed after agitating the carts to move fresh ink into the ink lines.
When the printer is used after a period of inactivity, and the ink has been allowed to settle in the ink lines, the clearer ink base will initially flow quite easily through the lines into the print heads. With less pigment than normal, the nozzle check will still look quite normal. But this ink gets followed later by ink that may be actually thicker or thinner than it should. Quite often the pigment in the ink lines will get forced into the ink dampers at one time. Print quality immediately begins to suffer. Power cleanings will move fresh ink through the printer as long as too much pigment has not been allowed to settle in the ink lines.
Some of our customers will test their printer with old Epson inks that have been setting for months and see that it prints a nozzle pattern after a head cleaning. Then after printing a short while, the settled pigments from the older Epson inks begin to fill in the dampers and block ink flow to the print heads. This is why we ask customers to fully test their printers before switching to our inks. We do not want to inherit the issues caused by old settled inks.
Looking at pigment settling requires two considerations: what is left in the ink lines and what is left in the ink cartridges. The ink lines may have a thin layer of pigment lining the tubes that can cause the flow rate to be reduced. The act of cleaning the print head produces an enormous suction that will generate (possibly) a good nozzle check. But, printing produces only a small draw force and the printer can again return to missing nozzles. The customer notices that they have to clean their print heads constantly.
This is a Roland ink damper. It looks very similar to an Epson ink damper. Epson makes the inks that are sold as Roland. What happens in a Roland happens in an Epson. But, the main difference between the two printers which have similar print heads and ink systems is that the Roland printer costs a fortune and allows the customer to perform most of the routine maintenance such as damper and capping station replacements. Print heads are replaced in about 20 minutes. It can take a customer over an hour to just get to the dampers in an Epson printer. Dampers provide two functions. They control the flow of ink and they filter the ink. Dampers should be replaced annually or as needed.
As you can see it does not take much pigment material to “clog” a damper, or obstruct it enough to cause banding and striation problems when printing. Usually a nozzle check is perfect, followed by a few inches of printing, maybe feet…but then an ink drops out or begins to band. Cleaning the nozzles pumps fresh ink into the heads and the problem reoccurs while printing. Old ink? maybe… Old damper? most definitely…
Pigment settling can plug a damper quickly. This particular example is of a yellow position damper that has had less than one cartridge of Roland yellow pigment ink printed through it in a period of only 2 months. The yellow began printing with striations and drop outs. Removing the damper and flushing with some distilled water reveals the reason why. A small amount of pigment matter has collected on the filter screen. Even this small amount can obstruct ink flow at the rate that the print heads require. We think that this is unusually short time for pigment to begin clogging a damper, and we suspected that we had installed an out-dated yellow cart. We easily switched the Roland pigment printer from Roland inks to ConeColor inks.
We believe that customers should take responsibility for their printer maintenance in a way that prevents problems caused by inactivity or intermittent ink use.
One alternative is to invest in a printer flushing system that can be used to fill the ink lines, dampers and print heads with a safe storage solution when the printer is going to be stored for a month or longer. We formulated PiezoFlush which is as strong a solution as possible to clear actual “clogs”, yet safe enough to be used for long term printer storage. It will not dry out quickly. It is designed to stay wet.
We encourage users of both EPSON inks and our inks, who are intermittent users or who must shut their printer off for extended periods, to purchase a second set of refillable cartridges and a quantity of our PiezoFlush fluid. The idea behind this is to remove the ink cartridges and insert PiezoFlush cartridges in their place. By performing two to three power cleanings, PiezoFlush is pulled through the ink lines into the dampers and out the print heads into the capping station. Then the printer is turned off.
Returning the printer to “print mode” is the same process once the PiezoFlush carts have been replaced with the ink carts. Before the ink carts are installed, they are gently shaken to redistribute the pigment into suspension. EPSON carts can simply be shaken for five to ten seconds. Refillable carts are generally turned downwards so that the ink outlet is towards the floor and and the air vent (if present) is towards the ceiling – and the cart is gently shaken so that ink does not come out the air vent.
We have also warned our customers that they should gently shake their refillable carts about every three weeks if they are light printers. We sometimes gently shake our printers which transfers the shaking motion to the ink carts. But, in both our studios (Cone Editions Press) and in our R&D labs, if we are not going to use a printer for more than a month we definitely remove the inks and install PiezoFlush. This holds true for both our EPSON Ultrachrome printers (which we produce EPSON comparative ink samples on) as well as our ConeColor and Piezography printers.
In the meantime – we sell PeizoFlush which is formulated and manufactured by Vermont PhotoInkjet on this page. PiezoFlush is stained pink so that you can see it. It is used as a print head cleaner, a flush fluid, and a storage fluid.