A process of formulating a curable thermoset resin formulation is provided that includes reacting a natural cellulosic filler with at least one of: a silsesquioxane, a isocyanate, a base, or an organic acid to form a reduced hydrophilicity filler. By intermixing the resulting reduced hydrophilicity filler with a thermoset cross linkable polymeric resin, a curable thermoset resin formulation is formed that has superior properties to conventional formulations in terms of density and environmental impact. The formulation properties in terms of strength of the cured article are improved relative to untreated natural fillers. The treatment is advantageous relative to plasma treatment. An article is also provided produced upon cure of the formulation.