Water-based paints nowadays consist of an acrylic emulsion technology developed during World War II by chemists Otto Rohm and Otto Haas. More than 80 percent of paints used today are water-based paints, compared to 70 years ago when the only option available to homeowners were solvent-based -- oils or alkyds -- paints made from resin. Compared with water-based paints, solvent-based paints contain considerably more organic compounds that emit noxious fumes as the spreading agent dries.
Sherwin-Williams developed the first water-based latex paints. Natural latex comes from the rubber tree, but for the paint, the developers used a synthetic latex as the vehicle for the paint pigments and binders. After Rohm and Haas invented acrylic emulsion technology, by the 1970s, water-based acrylic paints became synonymous with latex paints.
Spreading Agents, Pigments and Binders
The paint's spreading agent can also help clean up tools after painting. The spreading agent in water-based paints is obviously water; in oil-based or alkyd paints, you need a petroleum-based solvent for cleanup. Both water- and oil-based paints use the same pigments to add colors to the paint. Binders in the paint make the color particles adhere to the painted surface. Water-based paints use acrylics as the binding agent, which is why these paints have an elasticity to them when they dry. In solvent-based paints, the binder may be an alkyd or natural oil.
Water-Based Paint Advantages
Water-based paints are used more than oil-based paints thanks to their many advantages:
- Lower health risks because of lower volatile organic compounds
- Multiple coats can be applied same day -- quick drying
- Easy cleanup of tools with soapy warm water
- Paint colors don't yellow with age
- Flexible finish that resists cracking.
Oil-Based Paint Comparison
Oil-based paints have their advantages too; they provide a hard, glossy and opaque surface, which is why they're often used to cover doors, window trim, baseboards and moldings. Oil-based paints make good choices for areas exposed to constant water -- such as on the outside of your home. Some advantages of oil-based paints include:
- Hard, strong surface coat
- Nice spreadability
- The paint dries slowly, so brush strokes level out and disappear
- Smooth, scrubbable surface
- Excellent adhesion.
Which Paint to Use
The best paints to use inside your home -- especially if a family member has allergic sensitivities -- are water-based acrylic paints. In place of oil-based paints for trim, moldings and doors, use modern versions of latex enamel paints made with water and acrylics. For the exterior of the home, oil-based paints provide a durable surface. Outside, its offensive VOCs have less effect than inside the home.
Two-step epoxy paints use a catalytic agent, much like resins do, for areas that require resistance to acids, oils or solvents and abrasion, such as on a garage floor. These types of coatings work well for high moisture areas, below-grade application and on exterior block or cement walls cleaned with pressure washers. Epoxy paints work as primers or as finish coats, depending on needs. Once you mix the catalyst into the paint, you must use all of the paint, because it hardens as it cures.