Intumescent coatings provide exceptional passive fire protection for both metal and timber structures. These coatings have become exceptional popular both in school buildings and those for which housing associations are responsible for, due to how versatile and cost effective they are. But what actually are intumescent coatings?
Typically an intumescent coating will provide an appearance similar to a paint finish. Whilst the temperature remains ambient these coatings remain stable, however with an increase in temperature such as during a fire a chemical reaction occurs. This reaction results in the coating expanding to a number of times its original thickness, creating an insulating coating similar to foam, known as char, which protects the underlying surface from the fire.
Intumescent coatings can be utilised to protect both timber and metal substrates, however when covering these surfaces they perform slightly different functions. To demonstrate:
- Metal Substrates: When used in this application intumescent coatings are designed to insulate the metal, preventing it from reaching a critical temperature at which structural integrity becomes compromised.
- Timber substrates: Timber is far more susceptible to the spread of flames and heat propagation along its surface than metal. In this application intumescent coatings aim to reduce the spread of both flames and heat propagation.
What is the process by which intumescent coatings provide protection?
- The heat from the fire begins to soften the polymeric binder.
- This causes an organic acid to be released from the Ammonia Polyphosphate contained within the coating.
- Following this the carbonisation of the polyols commences.
- The blowing agent within the coating, melamine, begins to decompose. As it does the gas produced expands and swells the molten mixture.
- As the chemical reaction comes to its conclusion the foamed char solidifies, as part of a cross-linking reaction, in order to maintain the insulation.
Potentially intumescent coatings have the ability to expand up to 100 times its original thickness. However in order to achieve such an effect relies strongly on ensuring that the right formulation components are selected and the precise matching process is observed.
CJ Coatings Nationwide have specialism in applying intumescent coatings, including those manufactured by Envirograf, Nullifire, Thermoguard, Zeroflame and Firetherm. This specialism has been gained over year of intensive industry experience applying these coatings on behalf of our housing association and educational clients. For further information, or to arrange an onsite survey, a member of our dedicated customer service team can be contacted by calling 01908 467990.