In liquid penetrant inspection, when should the inspection of a test specimen for discontinuities occur?

In liquid penetrant inspection, when should the inspection of a test specimen for discontinuities occur?

• A. Before the developer has been applied.
• B. After the developer has been on for the proper development time.
• C. During development.
• D. After rinsing.

Answer: (B)

In liquid penetrant inspection, the reason to inspect after the developer has had its proper development time is that the developer draws penetrant out of any flaws and creates a visible indication on the surface. That development time lets the defect-related penetrant migrate to the surface and form a contrasting mark that you can see under the chosen lighting. If you inspect too soon, the indication won’t have formed, so you could miss a flaw. Inspecting during development isn’t the standardized end point, since the indications aren’t stabilized yet. After rinsing, there’s no penetrant left to develop into a visible mark, so you wouldn’t see proper indications. Following the specified development time gives consistent, detectable results.

In liquid penetrant inspection, the reason to inspect after the developer has had its proper development time is that the developer draws penetrant out of any flaws and creates a visible indication on the surface. That development time lets the defect-related penetrant migrate to the surface and form a contrasting mark that you can see under the chosen lighting. If you inspect too soon, the indication won’t have formed, so you could miss a flaw. Inspecting during development isn’t the standardized end point, since the indications aren’t stabilized yet. After rinsing, there’s no penetrant left to develop into a visible mark, so you wouldn’t see proper indications. Following the specified development time gives consistent, detectable results.