How does intumescent paint for steel react during a fire?

Intumescent paint for steel reacts to fire by expanding and forming an insulating char layer when exposed to high temperatures. This layer significantly slows down heat transfer to the steel, delaying its weakening and structural failure. Typically, steel begins to lose strength at around 550°C, but intumescent coatings help maintain its integrity for a specified period, allowing more time for evacuation and fire control. The expansion process occurs due to chemical reactions within the paint, which can swell up to 50 times its original thickness, providing crucial passive fire protection in buildings and industrial structures.