Nondestructive testing is used widely in the engineering and manufacturing industries for a variety of purposes.

As a testing and analysis technique used to study the materials, structure, or system without damage to the original part, nondestructive testing solutions can test for potential defects of materials and systems both at surface level and inside the material or system.

In using this method, facilities don’t have to compromise the integrity of materials or systems to inspect their quality.

There are several methods of nondestructive testing used in these industries including:

  • Acoustic emission
  • Electromagnetic
  • Ground-penetrating radar
  • Leak
  • Microwave
  • Liquid or dye penetrant

Nondestructive testing offers accurate and immediate results. Companies can learn more about how to improve the quality of their products, materials, and systems in real-time, without causing harm to their assets in the process. 

Dye Penetrant Testing, in particular, can help in determining fracture toughness and fatigue strength in certain materials. 

What is Dye Penetrant Testing?

Dye penetrant testing specifically tests for material or system defects at surface level and is used primarily for metals, certain plastics, and ceramics. 

The basic steps for dye penetrant testing include: 

  • Penetration of the defect in the material by the dye penetrant
  • Removal of the excess dye penetrant from the surface of the material       being tested
  • Development of the indication
  • A thorough inspection of the material, where its defect lies, and what can – be done to correct the defect  

Process of Dye Penetrant Testing  

Cleaning the Material  

 Before any testing begins, the material to be inspected needs to be cleaned completely. If there is a specific section of the material being tested, that section should be cleaned with cleaner/remover long enough to dissolve the dirt or other films that would have an adverse reaction with the dye penetrant. 

Applying the Dye Penetrant  

The dye penetrant is applied as a spray or with a brush (depending on the surface area of the material or system being inspected). The penetrant should remain on the surface for 10 to 30 minutes when covering a visible surface area. 

However, if you’re looking for defects in tighter or smaller spaces, a longer penetration time may be required. 

Removing the Penetrant 

After the penetration time has passed, the surface will be wiped clean with a clean cloth or towel. Removing any excess should be done with the same cleaner or remover used to clean the material before the dye penetration process began. This should be applied to a cloth and not just poured directly on the material’s surface. 

Applying Dye Developer  

The technician will then apply developer to the section of the material or system being inspected (either stirred into a liquid to brush on or in a spray can). The developer will spread and will display any cracks in the surface of the material or system. Depending on the size of the crack, some may take longer to appear more visibly. 

Inspecting the Material Surface Area 

A deep red indicator will appear with any surface cracks. A line or dotted line denotes a crack or forging burst. If the indicator spreads across the surface, this is indicative of a large crack that sits deep in the surface of the material. 

What Materials Can Undergo Dye Penetrant Testing?

Some of the most common materials inspected using dye penetrant testing include: 

  • Aluminum
  • Brass
  • Cast Iron
  • Ceramics
  • Copper
  • Stainless Steel
  • Certain plastics

By its flexibility in use across a large range of materials, dye penetrant testing is viable for a variety of facilities and industries using metallic/non-metallic, magnetic/non-magnetic, and conductive/non-conductive materials. 

Why Use Dye Penetrant Testing?

There are several industry benefits to using dye penetrant testing to test and inspect the quality of your materials. 

High Sensitivity 

Because the dye penetrant can detect everything from large surface cracks to the smallest breaks in the surface, it is widely referenced as a high-sensitivity testing method. 

Easy To Use 

Dye penetrant testing comes with the convenience of a quick and easy process. The rapid inspection capability of dye penetrant testing can quickly cover large material surfaces while also being transportable. This means technicians don’t have to carry around a bulk amount of equipment or chemicals to complete testing. Spray aerosol cans are portable and are usually available for this type of nondestructive testing. 


With many inspection techniques, you’re going off of basic senses to test the quality of a material or piece of equipment. 

Dye penetrant testing is one of the most visible forms of nondestructive testing, Indications of a surface break are plain to the naked eye with the help of the dye penetrant and the developer used, giving a quick visual overlay of where defects are and what you need to focus on for repairs. 

Low Financial Management 

Given the low cost of cleaners, dye penetrants, and developers, dye penetrant testing can be completed at a relatively low cost. 

You can test as often as you need to to ensure your materials and systems stay in good shape without having to break the bank. This means you can also reduce the potential risks of financial responsibility if accidents occur. Prevention and risk-based data can be acquired with basic and regular testing like dye penetrant testing. 

Choose NDT For Environmental and Industrial Resolutions 

In a highly competitive industry, you’re only as good as the service you provide. If your materials are faulty, you likely won’t be able to provide high-quality service to your customers. 

With our expert team of inspectors and structured in-house programs available, NDT Tanknicians can help you maintain quality control with dye penetrant testing and other non-destructive testing options. 

Contact us today to request a quote for inspections and testing in your facility.