Abstract: A method for making polyesterimide varnishes by polycondensing and imidat a mixture of trimellitic anhydride, 4,4'-diamino-diphenyl methane, glycol, dimethyl terephthalate and glycerol or tris(hydroxyethyl) isocyanurate or optionally p,p'-dihydroxy-diphenyl-dimethyl methane, with a transesterification catalyst added, and subsequently dissolving the resulting polyesterimide resin in an organic solvent with a crosslinking catalyst added, characterized by the feature that 2-methyl-1,3-propanediol and/or 2-butyl-2-ethyl-1,3-propanediol is used as the glycol or as one of the glycols.