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Non Destructive Testing // Penetrant

Water Washable Fluorescent Penetrant
  • Low to near zero background for assured indication visibility
  • Sharp, precise flaw indication for rapid interpretation
  • Excellent electrostatic spray capability
  • Long material tank life due to formula stability and non-volatility
  • Low material consumption (low drag out) due to low viscosity
  • Clean, odourless product, vapor free atmosphere


HM-406 is a level 2, Method A water-washable fluorescent penetrant for inspecting castings, extrusions and similar parts. HM-406 is a versatile, general purpose penetrant for use on a variety of materials, including aluminium and magnesium. Complies with low sulphur and low halogen requirements. HM-406 has been used by aerospace, airframe, turbine engine, and missile manufacturers for over a decade. 

Specifications Compliance

• SAE AMS 2644 & QPL – Type 1
• Method A, Level 2
• MIL-I-25135 Revisions C, D, & E
• SME Code NDT, Sec V
• Lockheed Martin
• MTU Boeing Rolls Royce
• Honeywell
• Turbomeca
• Pratt & Whitney FPM
• Airbus
• General Electric
• Northrop Grumman

Physical Properties

Colour: Green
Viscosity: 6.72 cSt @ 1000F
Fluorescence: Yellow/Green
Water Tolerance: 14%
Flash Point: 210°C


1. Application: Apply HM-406 only to clean, dry surfaces by spraying, flowing, brushing, or dipping.
2. Dwell Time: A 10-minute dwell time is suggested, although in many cases five minutes will suffice. When particularly tight cracks are suspected, or the part is especially critical, the dwell time may be extended to 30 minutes or longer. Allow the penetrant to drain from the part surface back into the penetrant tank to conserve material.
3. Removal:
a. Water Wash Method: Use ambient temperature water to rinse HM-604 from the part surface. To avoid washing entrapped penetrant from surface flaws do not use high water pressure temperatures and avoid prolonged washing times.
b. Solvent Wipe Method: Remove as much excess penetrant as possible using a clean, lint-free dry rag or towelling. Remove remaining penetrant film by wiping with a rag or towelling that has been slightly moistened with solvent. Use a minimum of solvent; avoid flushing penetrant from flaws. Do not spray the solvent directly on the part surface when removing excess penetrant. Rough surfaces require a more generous application of the solvent.
4. Drying:
a. A re-circulating oven set no higher than 71ºC is suggested. Leave the part in the oven just long enough to evaporate surface moisture. Drying is improved by using pressurised air to disperse and remove as much excess water as possible before placing the part into the oven.
b. When solvent remover is used, allow the surface to dry completely before applying developer.
5. Developing: Apply the developer by cloud, dusting, spray, or dip using the appropriate developer. Flaw marks are visible under black light almost immediately but allow sufficient developing time to enhance the flaw visibility.
6. Inspection: Inspect parts under appropriate UV-A light intensity and minimal visible light.

Ordering Info

1497/42 3.8 litres  (1 gallon)
1497/51 18.9 litres (5 gallons)
1497/64 208 litres (55 gallons)