“…The problem is further complicated when there is a change in the microstructure caused by chemical alteration of the material or exposure to high temperatures, as in the case of welding processes. In few occasions, a complete examination also requires techniques based on optical microscopy, such as color etching [1], which allows the microstructure of some materials to be studied in greater detail. Color etching takes advantage of the interference of light with reflections from the metal surface where the reactive agent has been deposited [2,3].…”