Pendulum hardness testers for paints and coatings – SA509

The pendulum hardness tester is an instrument designed to evaluate the surface hardness of dried paints, enamels and coatings by measuring the damping time of an oscillation. Once positioned on the coated surface, the pendulum is set in motion and the instrument measures the time required for the oscillation amplitude to decrease in accordance with the selected test method.

The pendulum hardness test is based on the response of the coating film to the stress generated by the oscillatory movement of the pendulum resting on its surface. A coating that damps the oscillation rapidly has a shorter test time and a lower surface hardness; whereas a harder film makes the pendulum oscillate for a longer period.

This method is particularly useful for comparing the surface behaviour of different paints or coatings after drying or curing. The test can be applied during formulation development, for verification of application and curing cycles, and as part of quality-control procedures on coated samples, providing an instrumental evaluation of surface behaviour.

The pendulum hardness tester is suitable for paints, enamels, protective coatings and finishes applied to flat panels that meet the requirements of the selected test method. It can be used to evaluate changes in surface hardness caused by differences in formulation, drying conditions, curing times or other process parameters.

Two procedures are available for evaluating coating hardness by pendulum: the König method and the Persoz method. Both methods evaluate coating behaviour by measuring oscillation damping, but they employ different pendulum designs and operating conditions. The appropriate method should therefore be selected according to the applicable standard, technical specification or inspection requirement.

Three configurations are available:

• SA509/K, fitted with a König pendulum for testing according to the König method
• SA509/P, fitted with a Persoz pendulum for testing according to the Persoz method
• SA509/K+P, supplied with both pendulums, suitable where the laboratory needs to perform both procedures according to different inspection requirements

The König pendulum is intended for tests performed according to the specific König damping procedure. The Persoz pendulum is designed for inspections requiring the corresponding Persoz method, offering a different configuration for assessing coating surface hardness. Results obtained using the two methods must be evaluated according to the relevant procedure and should not be regarded as directly interchangeable.

The SA509/K+P configuration is particularly useful when coatings intended for different specifications need to be inspected or when both König and Persoz tests must be carried out. Having both pendulums available allows different testing requirements to be managed using a single instrument

SA509 is equipped with automatic oscillation counting, helping to streamline test execution and result determination. The instrument also displays test temperature and humidity, providing useful environmental parameters for monitoring and comparing coating test results.

The SA509 pendulum hardness tester is used for testing in accordance with ISO 1522 and ASTM D4366, technical references for evaluating the surface hardness of paints and coatings through oscillation damping using König or Persoz pendulums.

The test is used in quality-control laboratories, during the development of coating products and when comparing finishes and coatings subjected to different drying or curing cycles. Measuring damping time makes it possible to check film surface behaviour under controlled conditions and compare tested samples using the same method.

The pendulum hardness testers for paints and coatings provide a dedicated solution for evaluating surface hardness according to the König and Persoz methods, with three configurations available to meet different testing procedures and inspection requirements.

Applications

• Assessment of the surface hardness of dried paints and coatings
• Pendulum hardness testing on enamels and protective coatings
• Quality-control checks on coated panels and samples
• Comparison between different formulations or application cycles
• Verification of film behaviour after drying or curing
• Measurement of pendulum oscillation damping time
• König pendulum testing using the SA509/K configuration
• Persoz pendulum testing using the SA509/P configuration
• Execution of both methods using the SA509/K+P configuration
• Testing in accordance with ISO 1522 and ASTM D4366

FAQ – Pendulum hardness testers for paints and coatings

What is a pendulum hardness tester used for?
It is used to assess the surface hardness of a dried paint or coating by measuring the damping time of a pendulum oscillating on the surface.

How does a pendulum hardness test work?
The pendulum is positioned on the coated surface and set into oscillation. The instrument detects the time required for the oscillation amplitude to decrease according to the limits specified by the applied method.

What does damping time indicate?
A shorter damping time indicates that the coating reduces the oscillation more rapidly and therefore has lower surface hardness according to the method used. A longer time is associated with a harder film.

What is the difference between the König and Persoz methods?
König and Persoz are two test procedures based on the same oscillation-damping principle, but they use different pendulums and operating conditions. The method to use depends on the applicable inspection reference.

Which model should be selected for a König test?
The SA509/K configuration, fitted with the corresponding pendulum, is suitable for testing according to the König method.

Which model should be selected for a Persoz test?
The SA509/P configuration, fitted with the specific pendulum for this procedure, is suitable for testing according to the Persoz method.

When should the SA509/K+P configuration be selected?
The SA509/K+P configuration is suitable when both the König and Persoz methods are required, for example to manage different inspection specifications with the same instrument.

Are results obtained with König and Persoz directly comparable?
No. The two methods use different configurations and operating conditions. Results must be assessed according to the applied procedure and compared with tests performed using the same method.

Which coatings can SA509 be used on?
It can be used on dried paints, enamels, finishes and coatings applied to flat samples compatible with correct test execution.

Why is it useful to display temperature and humidity during the test?
Environmental conditions can affect coating behaviour. Displaying them during the test helps document the conditions in which inspections are carried out and compare results more consistently.

Which standards does the SA509 pendulum hardness tester refer to?
The instrument is used for testing in accordance with ISO 1522 and ASTM D4366, references for evaluating the surface hardness of paints and coatings using König and Persoz pendulums.