ASTM D4366

Introducing ASTM D4366 – Industrial Physics  

ASTM D4366 is an international ASTM test method for measuring the hardness of organic coatings using a pendulum damping test. 

The American Society for Testing Materials (ASTM) is one of the most influential standard bodies in existence. Established in 1898, ASTM international exists to develop standardized test methods, specifications, practices, guides, classification, and terminology across a range of subject areas. 

The ASTM D4366 method covers the use of pendulum damping testers to determine the hardness of organic coatings that have been applied to plane rigid surfaces, such as metal or glass panels. 

There are two hardness testing methods based on different pendulum types covered in the ASTM D4366 method.  

•  ASTM D4366 test method A: König pendulum hardness test 

•  ASTM D4366 test method B: Persoz pendulum hardness test. 

This pendulum damping test is similar in content (but not technically equivalent) to ISO 1522. 

Significance and use of the pendulum damping test  

The pendulum damping test has been found to have good sensitivity in detecting differences in coating hardness, where hardness is defined as resistance to deformation. 

The two procedures given in ASTM D4366 embody the principle that the amplitude of oscillation of a pendulum touching a surface decreases more rapidly the softer the surface. However, these hardness testing methods differ in respect to pendulum dimensions and both the period and amplitude of oscillation. 

The difference between König pendulum and Persoz pendulum damping testing  

In general, the damping time of the König pendulum is approximately half that of the Persoz pendulum. 

The Persoz pendulum has a greater degree of discrimination than the König for measuring the hardness of soft coatings, but it may not be as suitable for testing hard, slippery films. This is due to its tendency to skid on surfaces with a low coefficient of friction. 

The interaction between the pendulum and the paint film is complex, depending on both the elastic and viscoelastic properties. Plus, it may not be possible to establish a precise relationship between the two types of pendulum tests. 

Our pendulum damping test equipment

So, how can Industrial Physics improve your ASTM D4366 pendulum damping testing?  

TQC König Pendulum for hardness testing
The König pendulum consists of an open framework connected by a crossbar with two balls attached to the under face. The lower end of the framework is formed into a pointer and a weight sliding on a vertical rod and attached to the crossbar is used to counterpoise the pendulum. The damping time, in seconds, for the oscillation amplitude of the König pendulum to decrease from 6°to 3° is measured.  

TQC Persoz Pendulum for hardness test 

The Persoz pendulum is made from an open framework with an upper crossbar that has two stainless steel balls inset to form a fulcrum. It also has a lower crossbar that forms the pointer. The damping time, in seconds, for the oscillation amplitude of the Persoz pendulum to decrease from 12°to 4° is measured. 

Be sure to check out the full Industrial Physics range of hardness test and measurement solutions. 

Hard-to-beat hardness testing support 

We’ve learnt a thing or two about paint testing and hardness testing over the decades. Now Industrial Physics is recognized as a brand that likes to bring new, innovative pendulum impact testers to market. 

We like to share our knowledge. Across the knowledgebase section of our website we publish lots of blogs on related subjects. First up, why not try this blog that explores the different types of impact testing equipment. Then you could try this one which describes how to protect your coating performance with scratch hardness testing. 

Need ASTM testing solutions? Get in touch  

If you have any questions about ASTM D4366 testing, or any aspect of the pendulum damping test, then just get in touch!

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