Category Archives: Information

Printer Ink: is it just coloured water?

Maybe it used to be… go back in time five years or so, before photo printers were invented, your average everyday inkjet printer would just have used black ink. The printer was a lot like your fax machine – used to print off text pages and maybe a limited graphic. So before the advent of photo printer’s people’s expectations of their desk top printer was fairly simple: does it pick up paper, without screwing it up; is the text legible; does it dry quickly without smudging.

Moving forward now to the present day and because cheap printer’s aren’t renowned for their longevity and that they don’t cost a king’s ransom (loads of Lexmark one’s are free with a new computer) – loads of people have got a printer which is also a photo processing unit, which they expect to produce better results than Max Spielmann’s! So if the ink used in these new photo processing units was just ‘coloured water’ how would the user feel if they spent good time and money on glossy paper and the prints were just washed out and faded before you placed them into the photo album?

To cut a long story short, the technology used in ink is amazing, it just has to be.. otherwise imagine the force of complaints from all the users. The major inkjet companies either employ or outsource hundreds and scientists to invent and test only the best ink for use in their printers. In fact it is a rumour that HP has a group of 16 scientists based in South America (location unknown/secret) whose sole purpose is to test recycled cartridges and their ink to see if they infringe their own ink’s patents/copyrights. HP have actually won some cases against a few large companies who have re-filled cartridges with ink that has infringed their intellectual property. How the infringement is determined is beyond this blog, but suffice to say that the ink used in these recycled HP cartridges must be damn close to the original stuff.

Also, what this suggests to me is that Hewlett Packard must be are worried that the re-cyclers are getting close to achieving similar results to their own original cartridges. I have seen the printed results from recycled cartridges being just as good as the original’s and I have also seen awful results that have white lines across the page and either pink or green hue throughout the printout. The end quality of the print-out is a result of many things – but the main one’s being the recycling process and importantly the quality of the ink used to re-fill them.

Anyway back to the point, just a few qualities that the ink must have these days are:-
> Fade resistance or colourfastness
> Have correct colouring – pigmented or dye based
> Be smudge resistant
> Fast drying
> Remain uniform in colour through time i.e. keep the colour and solvent mixed in the same proportion from the first print to the last one
> Have the correct viscosity, PH level and surface tension

Add to this all the complexities involved with how the different ink interact with each other, the paper and the outer environment and you can see that even though ink makes up around 80% of the ink it is not just colour water. A more detailed report on inkjet ink can be read here.

How do Ink Levels Work?

This is a good question…..

Mostly the level of ink shown on the screen is just an estimate. The only real accurate way to know the true level is with an optical sensor.

Canon’s older printers that used the BCI-3’s and BCI-6 range of cartridges detected the ink levels in this way – in the main this worked well – it was only let down if the sensor became dirty or obscured. Canon recently introduced their newer range of home and small office printers, that use the PGI-5bk and CLI-8bk/c/m/y range of cartridges. The new range of cartridges use almost the same casing’s as the older BCI ones, but have a chip on the cartridge itself which communicates with the printer. Between the printer and the chip they monitor or estimate the amount of ink left in the cartridge.

This new method is very similar to the way the ‘chipped’ Epson printer cartridges work. Epson introduced chipped cartridges 6 or 7 years ago, these are de-noted by their reference being prefixed with by a T, Eg the Epson C46 takes the T036 black and T037 colour cartridges. Basically the new cartridge chip has a counter in it – lets say it has 300 for an example – each time the printer prints a sheet of paper the counter ticks backwards. So you get your new printer and eagerly print off 20 sheets of homework, the counter on the chip has gone down to 280 and the graph on the computer screen reflects this use of ink by lowering the bar.

The printer manufacturers have worked out that on average a certain amount of ink will be used on a certain size of paper. It is quite accurate, but not foolproof and I think the manufacturer will always side with the cartridge being emptier than the reality. They have agreed that there is still ink left in many reportedly empty cartridges, but this is a safety feature to protect the printers head burning out. In most Epson and Canon printers the head is fixed in the printer and isn’t replaced each time a new ink tank is fitted, so if the printer runs dry and continues to print the excess heat in the head can burn it out, basically ruining the whole printer.

To sum up the levels of ink shown on your computer screen are not usually the actual levels, but an estimated amount. Also, problems can occur if the chip on the cartridge isn’t read properly by the printer – or the cached levels held by the computer disagree with the chip. Sometimes if this happens the printer’s software thinks that the cartridge has been refilled and blocks any further levels being reported and can even just say that there is a problem with the cartridge and not allow you to use the printer!