Home » Opinions » Inkjet Printers » Ink Technology

Ink Technology

Black is black, but also colour

It’s reasonable to expect that when you print a document containing nothing but black text and graphics you will use black ink. The more you print, the more black ink will drain from the black tank or cartridge in your printer. What's a bit more surprising is that, depending on the make of printer, ink appears to drain from the colour cartridge too.

The Epson and HP printers in this group test used about a quarter of their colour tanks when printing the black tank/cartridge to exhaustion. This isn't a small amount – it represents an extra cost of around £4 per tank for the Stylus Photo 830U and the Stylus Photo 900, while the Deskjet 3650 cost £3.50 extra per cartridge. This means around a penny per page extra for each ‘black’ page you print.

The cynical among you might feel this is another example of printer manufacturers ripping you off over the cost of consumables. It certainly means you have to pay more overall for your ink, but HP, at least, does give a reason for doing things this way.

HP claims that by laying down small amounts of coloured ink as well as the black, the density or blackness of the ink is improved, so you get a cleaner, darker print. This may work, but it's hard to see the mechanism, as the coloured inks are normally dye-based and need to sink into the nap of the paper to create their colours, while the black ink is pigment-based and the tiny particles of pigment sit on top of the paper. You'd think that any extra density from the coloured ink would be obscured by the black ink sitting on top.

And then there's Canon and Lexmark. From the tests we’ve just conducted on the i450, i850 and P707 printers, it appears no coloured ink is used when printing black. The question that follows is ‘Are the black prints from the Epson and HP printers noticeably denser or blacker than those from the Canon or Lexmark machines?’

We examined all six black text prints under good natural light and asked our assessors to rate the print quality. The test was again done without the judges knowing which print came from which printer and the Canon and Lexmark prints were unanimously judged the blackest. If HP's reason for using coloured ink is the correct one, all we can say is that it isn't working.

The HP DeskJet 3650 is already the most expensive printer to run, with a 5% black page (including colour costs) coming to 5.8p. And in case you wonder, you can't whip out the colour cartridge when printing a batch of black pages, as the printer requires both cartridges in place and with ink, before it will start a print job.

So, for the densest black print and the most economical use of colour, we would have to recommend either of the two Canon printers or the P707 from Lexmark.

comments powered by Disqus