Passi Test Plus is a tool designed to assess the real quality of stainless steel. It consists of a “probe pen”, which contains the electrochemical solution, and an external storage unit. By pressing the probe pen on the surface, Passi Test Plus measures and stores data on the open-circuit potential and nobility of a metal, thus measuring its corrosion resistance.
The test, which is neither destructive nor damaging, is fast (the result is given in 15 seconds) and numerical: while other, purely chemical passivation tests are based on colour interpretation (ferrocyanide test), thus offering a strongly subjective datum that is often distorted by superficial impurities, Passi Test Plus delivers an exact and indisputable numerical value.
The Passi Test Plus system is calibrated with zero as its discriminating point: if the value is higher than zero, then the stainless steel is passivated; if the value is lower than zero, then passivation is either scarce or non-existent. This makes it possible to compare different kinds of stainless steel: the higher the value above zero, the better the passivation of the stainless steel sample; the lower the value below zero, the worse the passivation of the stainless steel sample.