Why should you avoid altering the surface during VT surface preparation?

• A. To avoid obscuring or creating defects.
• B. To improve defect visibility.
• C. To calibrate equipment.
• D. To change surface color.

Answer: (A)

In VT, what you see on the surface is what you rely on to spot flaws, so the surface condition must be preserved. Altering the surface by grinding, polishing, or removing coatings can create new scratches or remove features that help reveal cracks, or it can mask existing defects, leading to false indications or missed defects. Keeping the surface as-found (within necessary cleaning to remove obvious contamination) avoids introducing artifacts that would mislead the inspection. While cleaning can help visibility in some cases, the reason to avoid alteration is specifically to prevent obscuring or creating defects. Calibrating equipment or changing surface color aren’t related to the integrity of flaw detection in this context.