Aqueous inkjet inks having metal nanoparticles for printing of conductive patterns or for other reasons can be printed employing heat energy within the range of current printers. For optimum printing the energy delivered would be about 2.9.times.10.sup.9 Joules/m.sup.3 or larger of volume of the heater stack, preferably not much larger so as to conserve energy. In embodiments the mole fraction of water in the ink would be greater than 0.9 computed with respect to only the liquid components of the ink and the ink would be heated by contact with the surface a heater heated to 1.5.times.10.sup.15 or more watts/m.sup.3 of volume of the heater stack. Embodiments of a silver ink will have greater than 12% silver and up to 27% silver by weight of the weight of the ink; the ink may have a viscosity of less than 3 Pa-s at 22 degrees C., preferably is less than 2.7 mPa-s; the ink may have a mole fraction of water greater than 0.87, preferably greater than 0.9, this mole fraction being computed with respect to all of the components of the ink.