A method of making a filled resin includes the steps of: Providing a wiped film evaporator with an internal evaporator chamber maintained under vacuum and having an internal chamber wall maintained at an elevated temperature; introducing solvent-borne particles and organic matrix into the internal chamber; and compounding the solvent-borne particles and the organic matrix in the internal evaporator chamber by forming a thin film against the internal chamber wall, the thin film including organic matrix and particles, and the vacuum conditions and elevated temperature being sufficient to remove solvent from the particles and organic matrix to provide the filled resin. Less than about 10% of the particles in the resulting filled resin are agglomerated.