What must the strike-off bar made of in this test method?

The strike-off bar used in the test method must be made of steel or high-density polyethylene because these materials provide the necessary rigidity and durability required for accurate measurements. Steel is known for its strength and stability, ensuring that the bar can effectively level off the material being tested without bending or losing shape. High-density polyethylene offers a lightweight option that is still resistant to deformation, making it suitable for repeated use in various conditions.

Using either of these materials helps maintain consistency and reliability in the test results. Other materials, like wood or standard plastic, might not provide the same level of performance, as they can be more prone to warping or wear under repeated use, potentially leading to inaccurate measurements in the testing process.