Product Data Sheet – ZYGLO ZL-2C, ZL-27A, ZL-37

Post-emulsifiable Fluorescent Penetrants

ZYGLO® ZL-2C, ZL-27A and ZL-37 are fluorescent post-emulsifiable penetrants designed to be removed from the test part surface by emulsifiers or solvent. Both
Method B lipophilic emulsifier ZE-4B and Method D hydrophilic emulsifier ZR-10E can be used to remove these penetrants. With a UV-A light source, indications will appear as a bright green-yellow fluorescence.

Our post-emulsifiable fluorescent penetrants have a high flash point, and are designed to be used in open dip tanks.

Chemical product icon - fluorescent penetrant


  • Bright indications
  • Minimal background fluorescence
  • High flash point
  • Available in medium, high and ultra-high sensitivity
  • Immiscible with water, which protects against over-washing and allows the penetrants to separate easily from water.


Defect location: open to surface

Ideal for:

  • Castings
  • Forgings
  • Extrusions
  • Welds
  • Rough surface finish

Defect examples:

  • Cracks
  • Laps
  • Seams
  • Delamination
  • Porosity


A blend of petroleum distillates, oils, alkyl aryl phosphate and fluorescent dyes.

User Recommendations

NDT Method Penetrant Testing, Fluorescent
Storage temperature 10°C to 30°C
Usage temperature 5°C to 55°C (bulk); -5°C to 50°C (aerosol)
Coverage 20 – 30m² per litre; 10 – 15m² per aerosol
Pre-cleaner SKC-S
Hydrophilic emulsifier ZR-10C
Lipophilic emulsifier ZE-4B
Developers SKD-S2, ZP-4B, ZP-5B, ZP-9F, ZP-14A
UV lamps EV6000, ST700

Product Properties

Form and colour Green-yellow liquid
Corrosion Meets AMS 2644
Flash point > 93°C
Sulphur content < 300 ppm
Chloride content < 300 ppm
Fluoride content < 50 ppm
AMS 2644 class Type 1, Method B/C/D
Property ZL-2C ZL-27A ZL-37
Density 0.89 g/cm³ 0.93 g/cm³ 0.95 g/cm³
Viscosity at 38°C 6.0 mm²/s 9.2 mm²/s 13.5 mm²/s
AMS 2644 sensitivity Level 2 (Medium) Level 3 (High) Level 4 (Ultra-high)
EN-ISO 3452 sensitivity Level 3 (High)

Like all Magnaflux materials, our post-emulsifiable fluorescent penetrants are closely controlled to ensure batch-to-batch consistency, optimum process control and inspection reliability.

Specification Compliance

Specification ZL-2C ZL-27A ZL-37
AMS2644 Yes Yes Yes
ASME B & PV Code, Sec V Yes Yes Yes
ASTM E1135 Yes
ASTM E165/E165M-18 Yes Yes Yes
ASTM E1417/E1417M Yes Yes Yes
EN ISO 3452-2 Yes
MIL-STD-2132D Yes Yes Yes
MIL-STD-271F Yes Yes Yes
Pratt & Whitney PMC 4352-2 PMC 4353-2 PMC 4354-2
Rolls Royce RRP 58003 (CSS 232) Yes Yes Yes
SAFRAN Pr 5000/In 5000 Yes Yes Yes

General Method of Use

Pre-clean the test part and allow to dry. The surface must be free from oil, grease and any other contaminant.

Apply the penetrant by immersion dip, brush, flow on, conventional or electrostatic spray. The test area must be completely covered with penetrant.

Allow contact time of 2 – 5 minutes minimum. 10 minutes should be adequate for most situations, although specific process specifications may require longer – check the controlling process specification (where applicable).

If you’re using a hydrophilic emulsifier, pre-rinse the test part with plain water before applying the emulsifier by spray (hydrophilic) or immersion (lipophilic). Leave for the required length of time then wash with a water spray.

The run-off from a pre-rinse can be treated to separate out the water, which can then be reused for other pre-rinses. Dye penetrant process rinse waters should not be discharged to local authority waterways or sewers without some form of effluent treatment. We can advise on suitable equipment for this purpose; for more information, please contact us.

Dry the test part by placing in a controlled recirculating warm air dryer at a temperature of 50°C – 70°C.

Apply a developer to maximise the sensitivity of the penetrant and to provide a white contrasting background. There are three types of suitable developer:

  • Dry powder: Free-flowing, lightweight powders which are applied to the dry component by powder storm, dusting, electrostatic spray or puffer.
  • Solvent-based: Quick-drying materials which are applied to the dry component by spraying.
  • Aqueous or water-based: Apply before drying by dipping or spraying. Note: To maximise penetrant sensitivity, do NOT leave parts in aqueous developers for any length of time.

Inspect your test part using a suitable UV source. Any defect indications will fluoresce a bright green-yellow when exposed to UV(A) light at a peak wavelength of 365 nm.

If required, you can clean your test part after inspection. Developer residues 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.

Packaging and Part Numbers


Part number 056C079

Packaging icon: 25 litre metal barrel

Part number 056C080

Packaging icon: 200 litre barrel


Part number 008A002
x 10

Packaging icon: 400 ml aerosol can

Part number 066C017

Packaging icon: 25 litre metal barrel

Part number 066C016

Packaging icon: 200 litre barrel


Part number 066C020

Packaging icon: 25 litre metal barrel

Part number 066C019

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 Sheets.

Download this Product Data Sheet as a PDF