wikiHow to Inspect Parts Using Dye Penetrant

These instructions apply to solvent removable penetrant systems.


  1. Image titled Inspect Parts Using Dye Penetrant Step 1
    Clean the part thoroughly using a suitable cleaner, acetone, aqueous degreasing, etc. Allow the part to dry. Drying can occur using a hair-dryer or in air. If air-dried, allow enough time for the cleaning agent to evaporate from the defects. This may take several hours depending on the ambient temperature and cleaning material used on the part.
  2. Image titled Inspect Parts Using Dye Penetrant Step 2
    Apply the penetrant to the surface being inspected. This can be accomplished by spraying, brushing, dipping, etc. Allow the penetrant material to sit for a minimum of 10 minutes. Do not let the penetrant sit on the surface for longer than 2 hours as drying may occur. The part and penetrant should beat a temperature between 50 and 100 degrees Fahrenheit.
  3. Image titled Inspect Parts Using Dye Penetrant Step 3
    Remove excess penetrant using a clean, dry, lint free cloth. Remove as much penetrant as possible using as many cloths as necessary. This is followed by wetting a lint free cloth with a solvent. The cloth must be damp or moist. A cloth dripping with solvent will wash the penetrant material out of the defect and make the test ineffective. Allow the solvent to dry before the next step.
  4. Image titled Inspect Parts Using Dye Penetrant Step 4
    Apply non-aqueous developer. The developer usually come in a spray can and is normally white. Apply a light coating holding the can about 6 to 12 inches (15.2 to 30.5 cm) from the surface. You should see visual evidence of the metal surface showing after applying the developer. Too thick of a coat will make the test ineffective.
  5. Image titled Inspect Parts Using Dye Penetrant Step 5
    The evaluation should occur using the proper lighting. Bright white light for visible dye penetrants and UV light for fluorescent type penetrants. Evaluating the results. This is the most difficult part of the testing process. Most people do not have a lot of experience with the different defect types, for example, porosity, shrink, cracks, etc.Porosity is typically round and easily defined, while shrink can look like a big blob of residual penetrant. Solvent wiping can help in determining the defect type and if the indication you are seeing is from a real defect or just an anomaly not associated with a defect. Solvent wiping is achieved by wiping the area of interest with a cloth dampened with solvent. Do not flood the area with solvent or allow solvent to run or pool on the surface as this may washout the defect and make it undetectable. As soon as the wiping occurs you can look at the indication to determine defect type

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