When it comes to fire-resistant intumescent coatings, there is a longstanding misconception in the industry: the belief that harder coatings perform better. Yet this approach can make it more difficult to select the right product for projects while causing time and cost advantages to be overlooked.

Why Hardness Alone Is Not a Criterion

In the coatings sector, hardness is generally measured using the Shore D durometer test. This method was originally developed to assess the curing levels of epoxy protective coatings. Over time, however, some applicators and project stakeholders have begun to regard hardness as the most important indicator of product quality. In reality, hardness is just one of many parameters to be evaluated. Particularly at low temperatures, harder materials can behave more brittly. When subjected to impact, the damage can spread over a much larger area compared with flexible coatings. By contrast, in more flexible systems, damage generally remains more localised and is easier to repair.

What Matters in Fire Resistance?

When assessed in terms of fire performance, hardness is not a direct determining factor. Fire-resistant coatings are certified through fire tests conducted in accordance with international standards. Notably, hardness values do not feature as a performance criterion in fire resistance certificates, because what truly matters from a fire safety perspective is the product's tested and approved fire performance.

Conclusion

Focusing solely on hardness values when selecting an intumescent fire coating is not the right approach. Application conditions, climatic factors, impact resistance, maintenance requirements and, most importantly, certified fire performance must all be evaluated together. The right product selection means not only a more durable coating but also a safer, more economical and sustainable fire protection solution.