The Mar resistance tester is used to assess the surface behaviour of paints, enamels and coatings subjected to controlled mechanical action. The test makes it possible to verify the ability of the coating to resist visible marks, alterations or surface damage caused by the sliding action of a curved loop-shaped stylus.
The Mar resistance test is particularly suitable where the appearance of the finish is an important coating requirement. A surface may maintain its functional continuity while still showing visible marring following contact, rubbing or stresses occurring during handling, assembly or use of the component.
The operating principle of SAMAR536 involves moving the coated sample beneath a loop-shaped stylus set at 45°, while the load specified for the test is applied. By progressively increasing the load, it is possible to identify the condition at which the surface film begins to show the observable damage considered by the applied method.
Unlike tests focused on coating penetration or localised failure, the Mar test is focused on the resistance of the finish to visible surface marks. It is therefore useful for inspecting coatings and painted surfaces where preservation of appearance must be assessed together with coating performance.
The Mar resistance tester can be used on paints, protective finishes, enamels and organic coatings applied to samples compatible with correct test execution. It is suitable both for laboratory activities and quality-control inspections, where the surface behaviour of samples produced with different formulations, application processes or drying conditions must be compared.
The possibility of applying progressive loads makes it possible to determine the level at which the surface begins to show the defect considered in the assessment. This information allows different coatings to be compared and helps verify which finish offers greater resistance to marring under the intended test conditions.
Mar resistance is a relevant parameter for coatings intended for applications in which contact with other elements, handling operations or end use may generate visible marks on the surface. The test can therefore be used in finish development, qualification of coating cycles and periodic verification of coating surface performance.
SAMAR536 is used for testing in accordance with ISO 12137 and ASTM D5178, technical references for determining the Mar resistance of paints and coatings using a curved stylus on surfaces suitable for the method. The procedure should be selected according to the coating type, substrate and required inspection criterion.
The Mar resistance tester SAMAR536 is therefore a specific solution for assessing surface damage on paints and coatings, identifying finish behaviour as the load applied during the Mar test increases.
Applications
- Mar resistance testing on dried paints and coatings
- Assessment of the Mar resistance of enamels and protective coatings
- Inspection of visible surface damage on finishes
- Comparison between different formulations or application cycles
- Verification of coated surfaces subject to contact and handling
- Quality-control checks on painted panels and samples
- Assessment of the load at which coating marring appears
- Mar testing with a curved loop-shaped stylus
- Testing in accordance with ISO 12137
- Testing in accordance with ASTM D5178
FAQ – Mar resistance tester
What is a Mar resistance tester used for?
It is used to assess the ability of a paint or coating to resist visible marks and surface damage caused by controlled mechanical action.
What is a Mar resistance test?
It is a test used to determine the resistance of a coated surface to visible marring. The sample is moved beneath a loop-shaped stylus set at 45°, applying the load specified by the method until damage to the finish becomes visible.
How does SAMAR536 work?
The coated sample is moved beneath the loop-shaped stylus and subjected to the load specified for the test. By increasing the load, the condition at which the coating begins to show the surface damage considered in the inspection is identified.
What does the Mar test result indicate?
The result makes it possible to assess the load level at which the finish shows the marring or visible damage specified by the method, allowing different coatings to be compared.
Why check the Mar resistance of a coating?
The inspection is useful where surface appearance must be maintained during handling, assembly or use of the component. A finish with limited resistance may show visible marks even without complete coating detachment.
Which coatings can SAMAR536 be used on?
It can be used on paints, enamels, protective finishes and coatings applied to samples compatible with the instrument configuration and selected test method.
Does the Mar test measure coating thickness?
No. The test does not measure film thickness; it assesses resistance to surface damage caused by marring.
Does the Mar test measure coating adhesion?
No. The test is intended to assess resistance to surface marring. Specific methods must be used to verify coating adhesion to the substrate.
In which activities can SAMAR536 be useful?
It is useful in finish and coating development, comparison of different application cycles and quality-control checks on painted surfaces where surface appearance is an important requirement.
Which standards does SAMAR536 refer to?
The instrument is used for testing in accordance with ISO 12137 and ASTM D5178, references for determining the Mar resistance of paints and coatings.
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