The resins for solvent-based paints are linseed or soya oils and alkyd resins. Most enamel paints are alkyd resin based. Varnish may also be created from synthetic resins such as acrylic, alkyd, or polyurethane. They are also used in alkyd resins, adhesives, surfactants, as fuel oil additives, lubricants, etc. Succinic acid is a precursor to some polyesters and a component of some alkyd resins. Polyols used in the production of commercial alkyd resins are glycerol, trimethylolpropane, and pentaerythritol. Modern commercially produced varnishes employ some form of alkyd for producing a protective film. TMP is mainly consumed as a precursor to alkyd resins. Metal naphthenates have been used as additive driers in alkyd paints. There are two types of alkyd resins, drying (including semi drying) and nondrying. Enamel paints are oil, latex, alkyd, and water based. Approximately 200,000 tons of alkyd resins are produced each year. Classic alkyd enamels would fall into this category. The first is a blend of an amino resin and an alkyd. Liquin is a quick-drying medium for oil and alkyd paint.