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Properties of Epoxy Intumescent
Base material and the cast version
Intumescent fire protection products which swell and then form a solid foamed ‘char’ in reaction to the heat of a fire have been around for many years. Epoxy intumescent is basically heavily filled intumescent in an epoxy medium. It may also contain carbon fibres to increase flexibility and provide added insulation. But it is the medium that makes the big difference. This is the key to epoxy intumescent’s superior longevity and durability.
The other important and distinguishing attribute is its much lower expansion rate. The expansion for thin-film intumescent is between 50 – 75 times, whereas the rate for epoxy is only x 5 – 8.
The high expansion rate of thin-film intumescent means that sufficient clear space needs to be allowed between the coating and the secondary cladding. When it comes to decorative columns, this can result in a broader diameter and less pleasing look than originally intended. When cast in the way Interactive Columns are produced, the advantages of epoxy intumescent are obvious. The castings themselves preclude the need for any secondary cladding. They provide their own decorative finish, and result in a sleek and much slender-looking column.
Interact’s ability to mould epoxy intumescent into virtually any shape required means that its cast product is ideally suited to circular and rectangular hollow sections, cast iron columns, specialist architectural detailing, and other specific applications where such flexibility is needed.
The method of manufacturing these castings results in a highly decorative finish that can produce many different surfaces and colours. The most popular and cost-effective of these is the lightly textured finish. This effect is achieved by rolling the top coat (rather than spraying in difficult on-site conditions). Finer profiles can be produced as the base casting’s outer surface is very smooth.
By contrast, it should be pointed out that some wet epoxy intumescents can only be applied to a maximum of 4 – 6 mm per coat when sprayed and trowelled. The finish is poor and also labour-intensive. They also require up to 22 mm of material to achieve 3 hours fire protection to cellulosic standards. This involves as many as eight coating processes, including wire mesh and surface finishes. The Interact cast system reduces this to just three (adhesive, casting, and top seal).
The cast epoxy shell is manufactured to allow for a 2 mm coat of epoxy intumescent adhesive which is used to attach the casting to the column—and may include a mechanical fixing system to meet the required fire standard.
Interact’s castings are manufactured under factory conditions, while the product is quality assured for repeatability of profile and thickness.