Modern fire-retardant developments

The advent of synthetic polymers was of special significance since the water soluble inorganic salts defined up to that time were of little or no utility in these largely hydrophobic materials. Modern developments therefore were concentrated on the development of polymer compatible permanent fire retardants. Although a multitude of individual products have since been developed, Table II attempts to list the most significant developments with the largest impact on the direction of fire retardant chemistry. 

In more recent times, use of chemical treatments has been made in order to reduce the flammability hazard associated with the more flammable textiles such as cotton and linen. The significant patent of Wyld in 1735 describing a finishing treatment for ceUulosic textiles using alum, ferrous sulphate and borax, and Gay-Lussac s first systematic study of the use of flame retardants in 1821 have formed the basis for the more recent and modern approaches to developing heat and fire resistant textiles. 

Most fire-retardant formulations are not resistant to leaching by water. Therefore, there have been increased efforts to develop leach-resistant chemicals that can be impregnated into wood products for use in exterior or high-humidity applications. Some of the proposed leach-resistant systems include chemical combinations that form insoluble complexes, amino-resin systems, and monomers that polymerize in the wood. A common amino-resin system for exterior use is di-cyandiamide phosphoric acid formaldehyde. Guanylurea phosphate-boric acid also is a commonly used organic phosphate salt for modern commercial fire-resistant wood. 

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