Protect Your Coating Performance with Scratch Hardness Testing

You want a coating to be long-lasting, durable, and great looking – and one of the best ways to make sure it will stay that way is with a great testing process. A key part of any thorough QA for coating is the scratch hardness test, read on for more details.  

Why do coatings need hardness testing? 

Hardness testing gives you an idea of how well a coating will withstand scratches when it’s subjected to the kind of conditions it is likely to experience. It can also determine other properties of a coating, including adhesion, lubricity, resilience, as well as the influence of coating thickness and curing conditions. This can help you work out the optimal thickness and application conditions to ensure the best possible performance.  

What is scratch hardness testing?

Scratch hardness testing uses a sharp object to measure how easily a surface is scratched. It can be used to test a wide range of materials and coatings and is used to determine how resistant a coating or material is to fracture or deformation when subjected to friction.  

The Mohs scale is used to measure scratch hardness and the measurement is typically taken with the help of a sclerometer. Scratch hardness testing is often performed in conjunction with other hardness tests, such as Rockwell hardness testing or Brinell hardness testing.  

How to perform a scratch hardness test 

To carry out a scratch hardness test, a mechanised scratch hardness tester is recommended. This allows you to clamp a test panel which is slowly moved whilst a stylus or alternative tool scratches the surface. The amount of pressure it takes to affect the surface allows you to determine the relative hardness of the surface. Depending on test procedures, specified or variable loads can be applied to obtain different degrees of failure, from trace to destruction. 

Typical scratch hardness testing process 

If you’re carrying out a scratch hardness test using a mechanized scratch tester, then the process may vary depending on the make and model but will follow a procedure close to the one below:  

1. Check suitable needle/stylus is fitted.  
2. Clamp test panel to slide.  
3. Load needle arm with weights to determine threshold of failure,  
4. as specified for go/no go tests. Or  
5. progressively increasing load until failure occurs.  
6. Actuate slide. If failure occurs, needle on voltmeter will flick over.  
7. Only conductive metallic panels will be suitable for this test result.  
8. Remove panel for visual assessment of scratch.  

TQC Sheen scratch hardness tester

Mechanised Scratch Testing Machine – 705 

If you’re looking for a fast, accurate and reliable method for scratch hardness testing, then we recommend our TQC Sheen 705 machine. It comes with weight set required by ISO 1518-1. The weight set specified by the preceding international standard, ISO 1518, is optionally available, allowing you to ensure you’re testing to meet common industry standards.  

Test your coatings with Industrial Physics

No matter what your coatings are, you’ll find the appropriate testing solution for them at Industrial Physics. With products created under the name of our specialist brand TQC Sheen, we’re known for innovation and quality in paints, inks and coatings – so you know we’ve got you covered. Whether you’re looking for scratch hardness testing or viscosity testing solutions, you’ll find plenty of quality TQC Sheen options.