Commercial solid tannery by-product ofwhite shavings of pickled hide was pretreated, to eliminate acid and salts, and hydrolyzed under alkaline mediumwith potassiumcarbonate at pH=10. The extracted gelatin (hydrolysable collagen) was used for surface treatment of paper sheets. The effect of gelatin concentrations (0.5-2.5%) onmechanical properties of treated paper sheets was studied. Adirect proportion was noticed between collagen concentration and improvements of paper properties. Paper sheets treated with 2.5%collagenwere subjected to thermal aging under different temperatures between 100-200°C for different intervals. Mechanical properties of aged paper sheets were investigated.