A red against white background discontinuity image is most likely to be seen when which penetrants are used?

A red against white background discontinuity image is most likely to be seen when which penetrants are used?

• A. Fluorescent penetrants are used
• B. Water-washable penetrants are used
• C. Solvent-removable penetrants are used
• D. Visible dye penetrants are used

Answer: (D)

A red-on-white indication comes from using a visible dye penetrant. Visible dye penetrants leave a colored indication that can be seen under normal lighting, so the defect appears as a red mark against the light background created by the developer. Fluorescent penetrants, by contrast, require UV light to make the indication glow, not appear as a red mark in ambient light. The terms water-washable or solvent-removable describe how the penetrant is removed, not the color of the indication, so they don’t determine the appearance.

A red-on-white indication comes from using a visible dye penetrant. Visible dye penetrants leave a colored indication that can be seen under normal lighting, so the defect appears as a red mark against the light background created by the developer. Fluorescent penetrants, by contrast, require UV light to make the indication glow, not appear as a red mark in ambient light. The terms water-washable or solvent-removable describe how the penetrant is removed, not the color of the indication, so they don’t determine the appearance.