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Non Destructive Testing // Magnetic Particles

Visible Magnetic Particle
  • Particles are easily agitated, fast acting and produce defined indications
  • Particles meet specification requirements
  • Can be used with both stationary and portable magnetic test equipment
  • Can be used at elevated temperatures
  • Water based suspension is non-flammable


DUBL-CHEK Black Oxide No. 1 is black magnetic oxide particle that can be suspended in a highly refined light petroleum oil or water. The particles respond to magnetic leakage fields created by discontinuities in ferromagnetic material. Particles rapidly collect at leakage fields producing black indications.

Specifications Compliance

• ASTM E3024
• MIL-STD-271
• NAVSEA 250-1500-1
• NTR-1E
• MIL-STD-1949
• AMS 3042
• AMS 2641

Physical Properties

Particle Colour: Black
Specific Gravity: 0.4 g/ml
Particle Size: 0.5 – 4.0 µm (average 1.5µm)
Temperature limit: 0°C to 50°C


Water Suspension: The water must be conditioned before adding the Black Oxide No.1 in order to disperse the particles wet the test surface and inhibit corrosion. W5-C is the recommended conditioner and is added at 10g/Lt. Black Oxide No.1 should be added at a concentration of 15g/Lt.
Settlement Test: The settlement test, using a pear-shaped centrifuge tube, is essential to check the particle concentration and contamination to the suspension. This SHALL be performed on the initial batch, an adjustment made to the concentration, or at each shift change. The Settlement Test methods and particle concentrations can be found in relevant standards. The recommended volume is between 1.2 and 2.5 ml and will vary from one specification to another. The concentration may be adjusted by adding more MPF, water or Black Oxide No.1 as required.

1. Clean the test surface and allow it to dry.
2. Apply DUBL-CHEK CP-2 for background contrast, if required.
3. Magnetise the area to be inspected.
4. Ensure continuous agitation of the suspension.
5. Apply the suspension to the test part at a distance of approximately 150mm from surface.
6. Allow the excess oil/water to run off the inspection area.
7. Inspect the surface under visible light.
8. Collections of Black Oxide No.1 particles will reveal discontinuities at the leakage fields.
9. Clean and repeat the process; changing the orientation of the magnetising direction.