Thermal ink jet printer

A method of ejecting a droplet of liquid from an orifice in a liquid-containing capillary, comprising the steps of:

• heating a portion of said liquid to a temperature which is below the boiling point of the liquid by passing an electrical precurser current pulse, which varies substantially as the square root of the inverse of time, through a resistor which is in thermal contact with said portion;
• and
• quickly heating said portion, by passing a subsequent electrical nucleation current pulse through the resistor, to a temperature above the boiling point of the liquid and near the superheat limit of the liquid to cause formation of a vapor bubble in said liquid-containing capillary, said vapor bubble causing a droplet of liquid to be ejected from said orifice.