Product Data Sheet – BYCOTEST RP20

Water-washable Visible Penetrant

BYCOTEST® RP20 is a water-washable visible penetrant that is also post-emulsifiable for greater resolution of flaw indications. It produces a visible red colour contrast, and features outstanding penetrating characteristics. RP20 offers maximum reliability in locating surface-open flaws and discontinuities, and can be used on non-porous ceramics and similar materials.

Chemical product icon - visible penetrant


  • Outstanding penetrating characteristics
  • Vivid, high-contrast color
  • Superior flaw resolution
  • Wide range of applications
  • Excellent controlled washability over a wide temperature range and variable dwell times.


Defect location: open to surface

Ideal for:

  • Castings
  • Forgings
  • Welds
  • Pressure vessels
  • Tubular goods
  • General metal work
  • Leak testing
  • Use in power plants
  • Construction applications.

Defect examples: cracks and leaks

Specification Compliance

  • ASME B & PV Code, Sec V
  • ASTM E165
  • EN ISO 3452-2 (Sensitivity Level 2)


A blend of petroleum distillates, non-ionic surfactants and an oil-soluble organic red dye.

Product Properties

Form and colour Red liquid
AMS 2644 class
Type 2, Method B/C/D
Flash point 63°C (bulk product)
Density 0.83 g/cm³
Viscosity 3.8 mm²/s
Sulphur content < 200 ppm
Chloride content < 200 ppm

Like all Magnaflux materials, RP20 is closely controlled to ensure batch-to-batch consistency, optimum process control and inspection reliability.

User Recommendations

NDT Method
Penetrant Testing, Visible
Storage temperature 10°C to 30°C
Usage temperature 5°C to 55°C (bulk product); -5°C to 50°C (aerosol)
Coverage 10 – 15m² per 400ml aerosol; 20 – 30m² per litre
Hydrophilic emulsifier ZR-10C
Solvent-based developers D30A, D30plus, SKD-S2
Accessories Reference test block (part no. 070C001)

Instructions for Use

Ensure test part is clean and dry, and free from oil, grease and other contaminants.

Apply penetrant by immersion dip, brush, flow on, conventional or electrostatic spray. Cover the test area completely.

Allow penetration time. Minimum penetration time is 2 to 5 minutes, with 10 minutes being adequate for most situations. Lower temperatures thicken the penetrant and require longer penetration times.

Remove excess surface penetrant with a solvent wipe or by the water-washable method (see diagrams opposite).

A developer is used to maximise sensitivity and provide a white contrasting background against which red indications can easily be seen. We recommend using a solvent-based developer, as it will be quick-drying and can be applied by spraying.

Ensure the test part is dry and apply a thin layer of the developer. Allow a minimum of 10 minutes development time before inspecting the component under normal daylight conditions. Any indications will appear dark red against the white developer background.

Developer residue can be removed either by wiping with a cloth or by a water and detergent wash. Penetrant residues can be removed by vapour degreasing or solvent soak.

Solvent wipe method

Clean the component. apply RP20 and allow contact time.

Wipe off excess penetrant with a cloth dampened with cleaner/remover.

Dry component, apply developer and inspect.

Water wash method

Clean the component. apply RP20 and allow contact time.

Remove excess penetrant with a water spray.

Dry component, apply developer and inspect.

Packaging and Part Numbers

Part number 008A178
x 10

Packaging icon: 400 ml aerosol can

Part number 060C078

Packaging icon: 5 litre metal can

Part number 060C080

Packaging icon: 200 litre barrel

Health & Safety

Review all relevant health and safety information before using this product. For complete health and safety information, refer to the relevant Safety Data Sheet.

Click here for the PDF version of this Product Data Sheet