From thermosetting plastics, alkyds and melamine resins are better than phenolic resins. These drying alkyds are cured in air. From these, the alkyds we know today were developed. Polyurethanes are comparable in hardness to certain alkyds but generally form a tougher film. By adding certain modifying resins, it is possible to produce thixotropic alkyds for decorative use. The original alkyds were compounds of glycerol and phthalic acid sold under the name "Glyptal". With alkyds typical methods include maleinization of unsaturated fatty acids with maleic anhydride. Alkyds has good solvent, moisture and UV light resistance. Alkyds are used in paints and in moulds for casting. Alkyds are also used in items such as resins and paints.