Alkyd resins are usually available in solution with a compatible solvent. The curing is generally at ambient temperatures and initiated with metallic driers, but with short oil alkyds, blended with compatible thermoset resins (urea and melamine formaldehyde resins), heat curing and baking is necessary. Thermoset alkyds are used on metal products such as furniture and license plates, and are solvent and chemical resistant.
Alkyd resins can be polymerized or modified with such materials as styrene, vinyl toluene, silicone polymers, epoxy, urethane, and others to improve various properties. The modification is most effective when done at the alkyd polymerization step during manufacture where the modifier becomes an integral part of the final resin. The alkyd/modifier co-polymers can show the strengths and weaknesses of both polymer types. For example, epoxy modified alkyds (epoxy esters) exhibit improved adhesion to metal (epoxy), ease of use, and lower cost (alkyd). The chemical resistance of the epoxy ester would not be as good as the epoxy system alone.
Alkyd resins have been used for many years. They are economical and generally have good performance characteristics. They do, however, have a few disadvantages. Typical alkyds cure or dry by oxidation. The oxidation process will slow down once the coating is dry, but it never completely stops. So as the coating ages it will lose flexibility and become brittle. Used on exterior wood, alkyd topcoats eventually crack and lose film integrity. Alkyds (unless modified) will also chalk and lose gloss when exposed to ultra violet light. White alkyd paints will yellow badly with age especially on interior surfaces. Alkyds also have a very high VOC level. Waterborne acrylics and acrylic blends have taken the place of many alkyd coatings