Wooden wall claddings and suspended ceilings are widely used in public buildings, but due to their ignitability and flame spread properties these materials cannot be used without appropriate fire protection. Pigmented FR coatings are widely known for this purpose, but they completely cover what is desired by architects, building owners and visitors – the beauty and natural appearance of wood.
Exolit 855 (TP) is a fire protection ingredient for transparent intumescent coatings on wood. It is a completely clear, almost colorless solution, enabling the combination of excellent fire and water resistance with light and dark wood surfaces (Figure 4). The product is a proprietary mixture based on liquid partial phosphoric acid esters. In combination with melamine formaldehyde resins it contains all the necessary reaction partners for an intumescent reaction, and reacts at lower temperatures than conventional systems. Therefore, the intumescent system can be applied on almost all wooden surfaces, e.g., solid wood, medium-density fiberboard, chipboards, plywood and veneered wood.
The intumescent system consists of a two-component formulation. Part 1 is represented by the melamineformaldehyde resin, several additives and the solvent (water). Part 2 contains Exolit 855 (TP), a hardener and further components. The pot life of the combined parts is about 3 hrs and can be easily applied using brush or airless spray gun. The guide formulation (offered by Clariant under a nondisclosure agreement) shows good flow and levelling properties. The coating cures at ambient temperature, is dryto- touch after 4 hrs and scratch resistant after 24 hrs. An additional topcoat may be beneficial for protection against high humidity and direct water contact.