The film hardness test (IS 101 Part 5 Sec 1) assesses the resistance of a fully dried/cured paint film to scratching or indentation — an index of cure development and in-service durability/abrasion resistance. It is conducted on a conditioned standard panel; an inadequately cured or under-conditioned film reads soft and fails, so the result is as much a cure check as a formulation check.
Key Requirements
•Test only a fully dried/cured film on a conditioned standard panel (see the test-panel clause)
•Apply the scratch/indentation method and load/criteria specified in IS 101 Part 5 Sec 1
•A film that passes resists the specified scratching/indentation without being marked/cut to the criterion
•Report the hardness result with film thickness and conditioning regime
•Judge against the paint product specification's hardness requirement (IS 101 provides the method, not the pass level)
Practical Notes
✓Low film hardness is very often an under-cure / under-conditioning artefact, not a bad paint — verify the drying/conditioning before condemning the product.
✓Hardness correlates with abrasion/handling durability; it is an early proxy for how the coating will survive service.
Common Mistakes
⚠Testing a film that has not reached its required cure state (reads falsely soft).
⚠Comparing hardness across different film thicknesses/conditioning without recording them.
⚠Treating the IS 101 method as if it set the acceptance level — the pass criterion comes from the product spec.