Fire-retardant vs intumescent
The difference between fire-retardant coating and intumescent coating
The difference between fire-retardant paint and intumescent paint lies in their chemical composition. The former contains fire-retardant or flame-retardant additives; the latter is formulated with intumescent additives.
At temperatures between 200 and 300°C, flame-retardant additives release oxygen-inhibiting substances: they produce carbon dioxide or generate water vapour, thereby lowering the combustion temperature. Between 300 and 400°C, fire-retardant coatings begin to crystallise. Essentially, a non-flammable vitrified layer forms a barrier for the wood.
Protective and insulating barrier
Intumescent additives react at 200°C by causing the coating film to swell. In this way, they create a protective and insulating barrier, delaying both combustion and the rise in temperature. Flame-retardant additives are normally used in coating systems applied to furniture, whilst the more reactive – but aesthetically less transparent – intumescent additives are incorporated into paints used for coating load-bearing structures and paints classified according to the European fire reaction standard. Therefore, a fire-retardant coating certified to Class 1 of the European Fire Reaction Classification will contain flame-retardant additives and will be more transparent and offer better performance, such as chemical and abrasion resistance, whilst a intumescent coating certified to a European Fire Resistance or Fire Reaction Class will be significantly less transparent and more sensitive to moisture and mechanical stress.