The use of synthetic alkyd resin for solvent-thinned (oilbase) paints has brought several advantages. One of the most useful is a special formula that makes the paint yogurt-thick. A brush dipped in it carries more paint to the surface than previous versions. Yet, under the friction of application, the paint spreads and smooths readily.
In most gloss and semigloss (or satin) paints, alkyd materials are still preferred for trim, doors, and even heavy-traffic hallways. Many homeowners still like them best for bathrooms and kitchens, where they feel more confident of washability despite the availability of water-thinned enamels in satin or gloss that can be safely cleaned with standard household cleaners.
The opacity of alkyd paints has improved with the addition of a material that diffuses and evaporates, which leaves minute bubbles that reflect and scatter light and makes the paint look thicker than it really is. With paints of this formula, one coat of white will completely cover black or bright yellow.
While alkyds should not be used on unprimed drywall (they can raise the nap of its paper coating) or unprimed masonry, they are suitable for raw wood and almost any previously painted or papered surface. The most durable of interior paints, alkyds are dry enough for a second coat within four to six hours. Solvents must be used for thinning and cleanup. Check the label to find which solvent is recommended by the manufacturer. And, while the solvents may be almost odorless, they're still toxic and flammable, so you should work in a well-ventilated room.