An ink containing a hydrophobic colloid charged with a positive zeta potential when the pH of the ink is within a range of over 4 and under 6. Silicon or silicon compound can be limited from being eluted into the ink from a circuit board formed from a silicon wafer or the like. Additionally, silicon or silicon compound, if eluted into the ink can be prevented from being deposited on a resistance heater and causing “cogation”, or to prevent the silicon or silicon compound from being deposited in an ink channel and nozzle to clog the nozzle.