Which of the following is NOT a function of developers used in penetrant testing?

The function of developers in penetrant testing is primarily to prepare and support the penetrant indications made visible during an inspection process. Developers play several key roles, including drawing contaminants away from the defects, which helps in revealing and accentuating the applicable indications. They also enhance visibility by providing a contrasting background against which the indications can be seen more clearly. Additionally, developers can assist in enhancing the fluorescence of the penetrants, especially when using fluorescent penetrants, making it easier to detect and interpret the indications.

Adding fluorescence directly to penetrants, on the other hand, is not a function of the developer. Fluorescence is a characteristic of the penetrant itself and is determined by the chemistry of the penetrant formulation, not by the developer. Thus, the developers do not contribute fluorescence but rather help to make existing indications more visible.