It is like printing gold

19 march 2011 - Formulation chemistry

The_secret_of_cardridge_ink.gif This week, in a most enjoyable episode of the new Dutch television program "de rekenkamer" (Audit office) which exclusively deals with the costs of stuff, it was all about the price of toner cartridges (Link). We all know you can buy a printer almost for free but from then on you spend fortunes on new ink. The program calculates a liter of ink costs you over 3000 euro's (an average cartridge contains 5 ml) or quoting one of the experts on the show with ink it is like printing gold. No surprise the ink manufacturers are secretive about ink formulations and they will not even patent them, according to the show. In a way ink is a curious concoction: it is supposed to stay a liquid to infinity while in the cartridge but is supposed to dry out once past the printer head.
Nevertheless the program tracked down a scientist from Eindhoven University of Technology who was willing to share a recipe and here it is: water 75%, pyrrolidone 4.99% , trimethylolethane 12.37% (this compound is labeled EHPD , not sure why), the sodium salt of EDTA 0.10%, MOPS 0.03%, ethylene glycol 0.28% (the structural formula as shown in the show is that of the diacrylate, needs to be sorted out), 2,4,7,9-tetramethyl-5-decyne-4,7-diol 1.25%, benzisothiazolinone 0.21% (biocide?) and finally Brilliant Black BN with 4.23%. The total combined costs are only 300 euro's which suggests the big ink companies make a fantastic 1000% margin.
In the show we see the scientist patiently adding all ingredients at once to a little bottle. But wait a minute: if it is that simple ink companies cannot keep the recipe a secret. Any analytical laboratory can flesh out a ink composition when exposed to GC, HPLC or MS. This blog thinks the sting is in the exact order in which you add ingredients and what treatments (heat , stirring) are used. Significantly the TUE formulation was not field-tested in an actual printer and why did it contain insoluble particles? (all ingredients are water-soluble?).

In any event please stop whatever you are doing right now research wise and start producing cartridge inks. Except of course those of you involved in illegal drugs, the only business on the planet more profitable.