Developer
Developer is a white powder or spray applied after washing off excess penetrant. It draws out penetrant remaining in cracks and produces a highly visible contrast indication.
Physicochemical mechanism of action
Developer contains chemical compounds that react with and pick up residual penetrant. This process forms a visible color or contrast indication in the cracks.
Metallurgical relevance & risks in welding
If the developer is not applied correctly, incomplete uptake of the penetrant can occur. This can lead to missing contrast indications and thus inaccurate crack assessment. In addition, faulty development can lead to poor surface finish or even corrosion.
Workshop practice & instructions
1. After washing off excess penetrant, apply the developer directly to ensure optimal penetrant uptake.
2. Apply the developer in a thickness of 0.5 to 1 mm to produce a clear contrast indication.
3. The time between applying the developer and evaluating the cracks should not exceed 24 hours to ensure maximum effectiveness.