Synthetic drying oils, which are esters of polyhydric alcohols with one or more unsaturated benzoic acids, and if desired, one or more monofunctional monocarboxylic acids of different structure, can be formulated into paints, varnishes, lacquers and enamels by blending with varnishes, varnish gums, cellulose derivatives and auxiliary components such as waxes, solvents, pigments and plasticizers.ALSO:Synthetic drying oils, which are esters of polyhydric alcohols with one or more unsaturated benzoic acids, and, if desired, one or more monofunctional monocarboxylic acids of different structure, are manufactured by the following processes: (1) the unsaturated benzoic acid is reacted with the partial ester of a polyhydric alcohol with a different acid or acids, e.g. a glycerol partial ester prepared by heating fatty oils with glycerol and, preferably, an ester interchange catalyst; (2) a polyhydric alcohol, a polyhydric alcohol ester, e.g. a drying or semi-drying oil, and sufficient benzoic acid to esterify the free hydroxyl groups present in the mixture are reacted simultaneously; (3) the simple polyhydric alcohol ester of the unsaturated benzoic acid is made by direct esterification with the acid or an esterifiable derivative thereof such as the anhydride or a halide thereof, or an ester thereof with an alcohol more volatile than the polyhydric alcohol to be esterified; (4) simple or mixed esters are also prepared by an ester interchange between a simple ester of the unsaturated benzoic acid with a low molecular weight monohydric alcohol and a polyhydric alcohol or a partial ester of a polyhydric alcohol, preferably with the use of catalysts such as litharge or sodium hydroxide. Suitable polyhydric alcohols are ethylene glycol, diethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, glycerol, erythritol, pentaerythritol, mannitol, methyltrimethylol methane and p : p1-di-(2-hydroxyethyl) benzene. As the unsaturated benzoic acid may be employed any benzoic acid in which the benzoic acid residue is attached directly or through an intervening carbonyl radical to an ethylenically bonded carbon atom, e.g. o-vinylbenzoic acid, o-(b -chlorovinyl) benzoic acid; p-vinylbenzoic acid (obtainable by hydrolysis of the corresponding nitrile), and the unsaturated keto acids produced by the condensation of sodium p-acetobenzoate with furfural, p-acetobenzoic acid with formaldehyde, acetaldehyde, acrolein, methacrolein, crotonaldehyde, p-anisaldehyde, benzaldehyde or p-methyl benzaldehyde, o-carboxybenzaldehyde with acetone or with acetone and furfural, and 2 : 4-diacetobenzoic acid with two molecular proportions of furfural. The monocarboxylic acids used for the preparation of mixed esters can be in pure form or mixtures and may be aromatic or aliphatic, open or closed chain, and, if the latter, monocyclic or polycyclic, saturated or unsaturated, straight or branched chain and substituted or not by other groups or atoms, e.g. halogen, which do not interfere with the esterification process. Specified acids are cottonseed oil acids, corn oil acids, dehydrated castor oil acids, perilla oil acids, oiticica oil acids, linseed oil acids, soya bean oil acids, chinawood oil acids, quinolinic acid, crotonic acid, phenoxyacetic acid, stearic acid, rosin and acidic natural resins. In examples: (1) p-cinnamoylbenzoic acid and linseed oil diglyceride in toluene are refluxed in an inert atmosphere of nitrogen, when the mixed ester is obtained; (2) linseed oil diglyceride, p-[b -(2-furyl) acrylyl] benzoic acid and toluene are similarly refluxed. The esters can be formulated into paints, varnishes, lacquers and enamels by blending with varnishes, varnish gums, vinyl or urea-formaldehyde-type resins, cellulose derivatives and auxiliary components such as waxes, solvents, pigments and plasticizers. Modified alkyd resins are obtained by reacting a mixed glyceride of linseed oil acids and p-cinnamoylbenzoic acid with glycerol until alcoholysis has taken place and reacting the free hydroxyl groups present with phthalic anhydride. The Specification as open to inspection under Sect. 91 comprises also the manufacture of products similar to the mixed esters described above by blending a mixed ester having a higher content of the unsaturated benzoic acid ester than desired, with that amount of drying oil or other ester, whose acids are being used, which is calculated to give a mixed ester of the desired proportions. This subject-matter does not appear in the Specification as accepted.