Two of the most talked-about passive fire protection options are intumescent coatings and the newer LDH (layered double hydroxide) retardants. They both slow down fire, but the way they work — and the surfaces they suit — are very different. This comparison will help you pick the right one.
How intumescent coatings work
Intumescent paints are designed to swell. When they get hot, they expand into a thick, foamy carbon "char" — sometimes many times their original thickness. That char insulates the material beneath, which is why intumescent coatings are the standard for protecting structural steel in commercial buildings.
The trade-offs: they're often thick and opaque, frequently solvent-based, and the protective char depends on the coating being applied at the correct thickness.
How LDH coatings work
LDH takes a different route. Instead of swelling, it absorbs heat, releases water vapour and leaves a mineral residue. It's typically thin, clear and water-based. Because it doesn't rely on building a thick char, it works beautifully on materials where appearance matters — wood, paper, fabric and bamboo. Learn the full mechanism in what is LDH fire retardant.
Side-by-side comparison
| Factor | LDH (Aeon Core) | Intumescent |
|---|---|---|
| Mechanism | Heat absorption + water release + mineral shield | Swells into insulating char |
| Appearance | Thin, dries clear | Thick, usually opaque |
| Carrier | Water-based | Often solvent-based |
| Halogen-free | Yes | Varies |
| Best for | Wood, paper, fabric, interiors | Structural steel, heavy timber |
| Indoor / occupied use | Low-odour, non-toxic | Ventilation often required |
Which one should you choose?
Choose intumescent when you're protecting structural steel or heavy timber that needs a certified fire-resistance rating and appearance doesn't matter.
Choose LDH when you're protecting the everyday cellulosic materials that fill our homes and workplaces — furniture, panelling, curtains, packaging — and you don't want to trade away looks, air quality or ease of application. See the full breakdown on our comparison page.