Influence of flakes impregnation with salt flame retardants on selected physical and mechanical properties of OSB. In this study, selected physical and mechanical properties of OSB made from flakes impregnated with two fireproof agents: A) on the basis of quaternary ammonium compounds and boric acid and B) on the basis of diammonium hydrogen phosphate, citric acid and sodium benzoate. It was concluded that impregnated flakes increase fire resistance of the material, reducing the mechanical properties at the same time.