Tempo:
Alkyd and Latex Coatings Most paints, varnishes and stains used for the interior and exterior protection of walls, trim and other general purposes can be categorized generally as having either an alkyd or a latex resin base. Alkyd coatings: Alkyd (oil) resins are used for the manufacture of general purpose paint, varnish, and stain. Alkyd paints containing a large amount of linseed oil give paints flexibility properties, which are important when they are used as exterior primers and paints. Increasing the amount of alkyd and reducing the amount of linseed oil results in a hard interior/exterior enamel desirable for high-wear surfaces. Mixing alkyd and polyurethane resins further increases the hardness, which produces a polyurethane enamel. Enamel paint has a high degree of durability and therefore a fairly high gloss. Latex coatings: Latex formulations contain latex as the resin, water as the solvent, and pigment such as titanium dioxide, extender pigments and colour pigments similar to those found in alkyd paints. Latex is used as the resin for paint, varnish and solid stains, but not for semi-transparent stains. Latex resin is comprised of small spheres of plastic material suspended in a water solvent. As the paint dries, the spheres coalesce to form a film that covers the painted surface. The amount of resistance the finished surface has to abrasion from wear and scrubbing depends on the extent to which the pigment is covered by latex. As the latex resin content increases relative to the pigment, the gloss and durability increase, but the hiding power of the coating to conceal subsurface irregularities decreases. Exterior and interior latex coatings differ in the type of latex used for the resin. Acrylic latex is the most used resin for exterior products. More economical PVA latex is commonly
used for interior applications. For high quality interior paint, a blend of PVA and acrylic or straight acrylic is used. Acrylic has better adhesion qualities than PVA. Acrylic latex paint would therefore be better for coating over alkyd paint than PVA resin latex.
Comparison of Alkyd and Latex Most alkyd paints contain some vegetable oils such as linseed oil that have a tendency to yellow with time. Because latex coatings do not contain any oil, they have better gloss and colour retention. Latex coatings dry faster and give less noxious odour than alkyd coatings and cleanup is done with water rather than the spirit or oil based solvents use for alkyd paints. Flat latex paint tends to be more durable on exterior surfaces than alkyd finishes because the latex is permeable and allows the moisture content of wood to adjust rather than blister the paint. This is not the case for gloss latex paints that have a permeability similar to alkyds. Alkyd coatings are still preferred for trim such as doors, frames and baseboards because they are harder, and flow better, thereby leaving fewer brush marks than latex coatings. Because latex coatings are more environmentally benign than oil-based products, their use is encouraged.
APPLICATION Proper surface preparation is essential to a successful coating finish. The application temperature is critical. Apply at temperatures above 10 °C (50°F) to surfaces that are dry, clean and dust free. If latex paint is applied at a low temperature, proper film formation will not occur, making it susceptible to peeling. At low temperatures, alkyd paint dries too slowly and is susceptible to damage.
used for interior applications. For high quality interior paint, a blend of PVA and acrylic or straight acrylic is used. Acrylic has better adhesion qualities than PVA. Acrylic latex paint would therefore be better for coating over alkyd paint than PVA resin latex.
Comparison of Alkyd and Latex Most alkyd paints contain some vegetable oils such as linseed oil that have a tendency to yellow with time. Because latex coatings do not contain any oil, they have better gloss and colour retention. Latex coatings dry faster and give less noxious odour than alkyd coatings and cleanup is done with water rather than the spirit or oil based solvents use for alkyd paints. Flat latex paint tends to be more durable on exterior surfaces than alkyd finishes because the latex is permeable and allows the moisture content of wood to adjust rather than blister the paint. This is not the case for gloss latex paints that have a permeability similar to alkyds. Alkyd coatings are still preferred for trim such as doors, frames and baseboards because they are harder, and flow better, thereby leaving fewer brush marks than latex coatings. Because latex coatings are more environmentally benign than oil-based products, their use is encouraged.
APPLICATION Proper surface preparation is essential to a successful coating finish. The application temperature is critical. Apply at temperatures above 10 °C (50°F) to surfaces that are dry, clean and dust free. If latex paint is applied at a low temperature, proper film formation will not occur, making it susceptible to peeling. At low temperatures, alkyd paint dries too slowly and is susceptible to damage.
©
2026
Lehal.net