What are the characteristics of the 3M colorimetric lead test?

The characteristic of the 3M colorimetric lead test is that it turns red due to sodium rhodizinate, which is a key component of the test's chemical reaction when lead is present. This method is designed to provide a visual indication of lead content by resulting in a color change, specifically to red, when it reacts with lead ions. The use of sodium rhodizinate is significant, as it demonstrates the specific chemistry that allows for effective lead detection.

The other options involve substances or processes that are not applicable to the 3M colorimetric lead test. Sodium sulfide, for instance, does react with lead but is associated with different testing methods and does not produce a red color. HEPA filtration is a method used in environmental controls but does not pertain to the chemical detection mechanism of lead. Methylene chloride, while being a solvent used in various chemical applications, is not used in this specific lead test, further emphasizing the specificity of the sodium rhodizinate's role in producing the characteristic red color.