POLYPHASE 641 is a solvent-based fungicide developed to provide enhanced chemical stability in solvent-based formulations containing driers, raw oils and/or transition metal pigments. POLYPHASE 641 is effective against a wide variety of fungal organisms. It offers excellent fungal protection and enhanced chemical stability in solvent-based systems that contain driers, transition metal pigments and/or raw oils. POLYPHASE 641 provides protection against fungi when formulated in organic solvent based systems. It contributes the added benefit of co-solvency when incorporated into organic solvent based formulations. POLYPHASE 641 is suitable for use in formulations and is suggested for the protection of millwork, including doors, windows, exterior siding, composite board, plywood and other construction lumber, when it is important to prevent the growth of fungi.