Quantitative Throwing Power

The effects, on levelling, of variations in agitation, pH and temperature are shown to be in accord with a hypothesis of levelling action put forward earlier. Measurements of levelling power on microgroove record masters are found to indicate satisfactorily the relative levelling action to be expected on commercially abraded surfaces. Cathode-potential measurements have been made with 60 addition agents in nickel solutions and with 30 in acid-copper solution, and where application of the hypothesis to the potential values promised strong levelling action, actual levelling powers were measured. In all such cases, high values were obtained. A method is described which permits rapid identification of levelling agents, by means of a simple cathode-potential change, Δ E^m. It is shown that a non-levelling agent such as saccharin can modify the behaviour of a levelling agent. Published Polarographic results are empirically related to levelling action, and it is demonstrated that certain groupings in the addition-agent molecule favour levelling.