Water and Oil-Based Paint
Paints are liquids that, when applied to a surface, dry to a solid film and impart color, protection and texture. Nothing spruces up a room faster than a new coat of paint, but the type you use depends on the surface you’re covering and the paint previously used, if any. The paint’s binder adheres to a surface and imparts durability, gloss and resistance to wear. The two main categories are oil-based and water-based paints.
Oil-based paints contain petroleum distillates and other organic solvents. They are often called alkyds and can contain various diluents, including ketones, esters, glycol ethers, alcohols, resins, aliphatics and aromatics. These paints adhere well, but can eventually oxidize and turn brittle, resulting in cracking, chipping and yellowing. Oil-based paints are preferred when you are covering chalked, or powdery surfaces, or ones that have several previous layers of oil paint. These paints take longer to dry, take longer to clean up and often have a strong odor. The solvents create a drag that slows application and results in thicker layers, which are useful when applying only one coat. If the solvent contains linseed oil, the paint may support mildew growth and therefore usually contain mildew-cides.
You shouldn’t apply oil-based paints to new masonry because it will tend to crack and chip quickly. You can however, apply a pre-treatment or sealer first. If you are priming the surface, oil-based primers work well with oil-based paints. Never use oil-based paint on galvanized metal.
Good old H2O is the main diluent in water-based paints. These are often called latex paints, but you’ll never find a drop of rubber in the can. You will find pigments or dyes in just about any color. Opaque pigments, such as titanium dioxide and red iron oxide, increase the hiding power of water-based paints. These paints have better durability, better color retention, more elasticity, less brush drag, faster drying times and less odor than their oil-based brethren. Clean-up with soap and water is easy, because you don’t need the solvents required for oil-based paints.
High-quality latex paints may have 100 percent acrylic binders that enhance durability and flexibility. They also adhere well to many exterior surfaces — especially wood, stucco, masonry, galvanized metal aluminum and vinyl — and are less likely to peel, flake or blister.
Overall, it is important to know what conditions the paint is being applied to. This will determine which paint is the best solution for each situation.