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Hazards of third party inks – double vision

#1121 – Double vision? In a print? Yes, it seems that an ink that is not formulated correctly for a print head can produce a replicated image effect similar to double vision. It’s enough to make you feel seasick! Read on for possible explanations, with illustrations.

StreakingStreaking from Third Party ink

There may be many symptoms of failure due to the use of third party inks and each of those symptoms may appear for one of a number of possible reasons. However, personally I am most familiar with either nozzle blockages or ink starvation causing either streaking or complete non-existence of image. So to discover a new and different failure was utterly fascinating – especially one as bizarre as this and that I did not instantly associate with the ink itself.

It was as a result of purchasing the pigmented third party black ink a few weeks ago (see for background) that this bizarre effect came to light. Once loaded into a suitable cartridge, and inserted into the printer, general printing continued until (as Murphy would have it) an important print job suddenly appeared looking like I’d printed it twice on the same sheet of paper in draft mode.

Double vision (close-up)Double vision (close-up)

As always, the first response is to try a reprint, then try cleaning the print head and attempting another reprint – no improvement at all! Stumped! It was only the realisation that the failure occurred precisely when the third party ink would have been expected to actually reach the print head, from the cartridge via the ink tubes, that made everything begin to fall into place in my mind.

It was then a simple matter to replace the cartridge containing the third party ink with an original and – sure enough – the double-vision image disappeared immediately (after purging the system of the third party ink) and all was well again – and continues to be well.

So, the next step was to try the cartridge in a different printer unit. The first one tried was a different unit of the same model – with precisely the same result. And again, returning to an OEM cartridge and cleansing the ink system returned the print quality to what we expect from an OEM system.

From there, the ink was loaded into a different cartridge for a different printer model – and different print head.

In this model, the result was different. There was no actual double-printing but the ink did cause the more familiar streaking. What it did do in addition to the streaking was to blur the image somewhat (taken to be a more muted version of the double image syndrome). Cleaning the print head had no effect at all. It was also noted that the density of black print from the third party ink was lower than print from the OEM ink and that droplets were not fired with the expected accuracy.

In a further printer unit (third model but same print head as model 2), again there was an element of streaking and low density print.

To date, it has not been possible to test the ink on other models. But, the fact that the print density is reduced (easily visible with just a cursory inspection of the print with the naked eye), we can determine that this third party ink is not appropriate for general use and, therefore, we will probably be using it only to test other ink systems as and when available.

So, what is going on?

As indicated earlier, it is possible for there to be number of reasons for the double-printing effect. What is clear is that:

  • the optical density of the third party ink is different from the OEM ink
  • the viscosity of the third party ink is different from the OEM ink

Lower optical density is demonstrated by the greyness of the resulting print while lower viscosity is demonstrated in the photo below where it is clearly seen that the drop of third party ink (right) does not stand as proud on the polished surface as the OEM ink (left).

ViscosityViscosity

An ink scientist, with access to sophisticated equipment to reverse engineer the ink and examine the behaviour of the ink droplet, would be able to identify all of the differences between the OEM ink and the third party ink, all of which could be significant to the ink’s performance.

Interestingly, in recent years, one of the successful actions brought by Hewlett-Packard against a third party supplier was specifically brought because the ink used by the third party WAS the SAME as the OEM ink! This may seem absurd but remember that the OEM has many patents on an ink. If the third party has reverse engineered the OEM ink and replicated it, then the patents are infringed. On the other hand, if the ink manufacturer contracted to the OEM sells the OEM’s ink to a third party, not only is it guilty of infringing patents but also of breaching contract terms designed to protect the formulation and the ink itself.

Coming back to the issue in hand, the precise reason for a failure of this nature will be different depending on the print head technology – thermal or piezo. In theory, both technologies could potentially produce this effect.

In this instance, the print head concerned is a piezo electric print head. So, it would appear that the most likely scenario is that the difference in ink viscosity has affected the speed at which the droplet is fired, thereby affecting exactly where on the paper the droplet lands. In addition, the difference in surface tension is probably changing the behaviour of the ink as it emerges from the nozzle. Amongst other possible implications (such as erratic droplet trajectory), this could be causing nozzles to flood, having the effect of cutting off the successful flow of ink to the paper in patches – ie causing streaking.

In a Thermal Inkjet system, the difference in viscosity of the third party ink could cause the ink to reach boiling point either more quickly or more slowly than the OEM ink. What this would do would be to cause the nozzles in the print head to fire either earlier or later than expected.

When printing black text in normal mode, this particular printer makes two passes over the paper – once in each direction – in order to ensure that the text is both dense and sharp. Because the nozzles are not firing at the prescribed time, the ink lands on the paper in a different place on pass two from where it had landed on pass one – hence double-vision!

Double Vision PrintingDouble Vision Printing

Here we are seeing an offset of a full millimetre … AND … erratic firing of droplets that disperse the image further, causing a total droplet spread of as much as 3mm! (the line on the original print these copies were taken from is only 0.3mm!)

Looking at the result of a print job printed in fast draft mode, we see this even more clearly. Here the print head makes only one pass over the paper to create the image and we see that there is a very clear offsetting according to the direction of travel of the print head. The lines should match exactly regardless of the print head direction.

Fast draft printing offsetFast draft printing offset

I cannot say that I am not disappointed that the refill pigment ink, sold as CISS (Continuous Ink Supply System) ink, has proved to be unusable. I am always on the lookout for ways to save money and that is, after all, what TCPglobal is all about. But – not at the expense of print quality, especially when it is as disastrous as this!

Incidentally – this is what an OEM ink copy of the same page should look like.

OEM ink copyOEM ink copy

What this experience emphasises is that users must be careful to manage their expectations when substituting OEM ink with third party ink. There may be a cost saving – but only if it works and print quality is acceptable. Otherwise, the purchase is wasted and the Total Cost of Printing for that user is unnecessarily increased. After all, the ink cannot really be returned once it has been injected into an OEM cartridge!

Experimentation is all well and good. But, with experimentation comes a degree of failure. It is hoped that the success outweighs the failure but, can an average user (home or business) afford the time and cost of experimenting to find a third party supply that really works to a satisfactory degree and also saves them money? It may just not be worth the hassle.

Keep an eye open – there may be more on this story as investigations progress.

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