Thermal ink jet printing presents some unique challenges to pigment-based inks. The process of superheating and vaporizing an ink at an elevated temperature can severely foul the heater and surrounding surfaces. Understanding the component interactions under these conditions can be beneficial to the design of stable and effective inks. Thermal ink jet devices configured for open pool operation are an especially useful tool to study the physical and chemical processes that occur during the vapor generation phase of the ejection cycle. These devices not only can be used for fundamental ink examination, but also as a predictor of ink performance in full ejectors.