Air pollution regulations, limited supply considerations, and toxicological problems frequently make substitution of one solvent for another necessary. A graphic technique has been developed which allows the formulation of replacement solvent blends on the basis of equivalent volatility or equivalent solvency for medium-boiling solvents such as methyl isobutyl ketone or methyl n-butyl ketone. Application studies indicate that these replacements derived by a graphic technique offer good starting point formulations in nitrocellulose thinners and vinyl lacquer solvents. -- AATA