What is Method A(W)?

Learn about the separate category for Method A penetrants according to AMS 2644 and what they contain in their formula.



Defining Method A(W) 

Method A(W) is a separate category for Method A penetrants and defined by AMS 2644 as a “Water Washable penetrant that contains 20% or more water by volume in its formula.” This category was added to the G revision of AMS 2644 and issued in April 2019. The current revision of AMS 2644 is H, which was issued in July 2020.  



Differences between Method A & Method A(W) 

For in use penetrant testing, Method A(W) has a different testing method and frequency for water content than Method A penetrant. The water content test is a quick weekly check for Method A(W) penetrants with the use of a refractometer.

If necessary, adjustments may be made by adding water or the Method A(W) penetrant to the tank. 


Features of Water-based Penetrants

Reliably Speed Up Inspection and Wash Processes 

  • Identify bright indications with superior sensitivity and low fluorescent background interference. 

  • Increase throughput and reduce costs by eliminating the developer step of inspection processes depending on procedures and requirements. 

  • Rapid rinse and post inspection washing of parts thanks to excellent washability properties.  

Reduce Waste-Water Pollutants and Environmental Footprint 

  • Reduce water treatment costs and discharge waste process water directly into the sewage system (depending on local regulations) due to minimal water-based contaminants. 

  • Meet or exceed local discharge regulations with low Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) levels. 

  • Support a healthy environment with water-based penetrants that have minimal environmental, occupational health and safety impact. 

Industry approvals  

  • QPL Approval 

  • ZL-425 and ZL-440 are approved and qualified to AMS 2644. 


Things to Know About Water-based Penetrants 

More frequent testing 

  • Method A requires a monthly concentration test by sending it into a lab or PeneCert program, while Method AW requires a weekly concentration test with a refractometer.  

Approvals Met 

  • If listed on QPL it meets the specifications for AMS 2644 as a Level I or 2 penetrant, depending on the classification. 

QPL Approval 

  • ZL-425 and ZL-440 are approved and qualified to AMS 2644. 

Lower Water Treatment Costs 

  • Disposal is a benefit for water-based or a deterrent for oil-based.  
  • Maintenance due to the concentration of the water-base.  
  • Wastewater treatments costs can be lowered. 

Application Method 

  • Water-based is not suited for spray application.  
  • Only referring to ZL-425 & ZL-440.  
  • Typically used in emersion tanks. 


ZL-425 ZL-440
Water-based, water washable level 1 fluorescent penetrant; contains no petroleum distillates allowing direct drain disposal. Water-based, water washable level 2 fluorescent penetrant; contains no petroleum distillates allowing direct drain disposal.
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