Abstract: The present invention is directed to the production of articles exhibiting high mechanical strengths which are relatively insensitive to changes in relative humidity. The articles consist essentially of organic and/or inorganic fibers and a binder, the binder being composed of the product of reaction between an organic polycation, and/or an aminosilane, and/or an organic chrome complex and crystals of a lithium and/or sodium water-swelling mica selected from the group of fluorhectorite, hydroxyl hectorite, boron fluorphlogopite, hydroxyl boron phlogopite, and solid solutions among those and between those and other structurally-compatible species selected from the group of talc, fluortalc, polylithionite, fluorpolythionite, phlogopite, and fluorphlogopite.