Oil-Based Paint Versus Water-Based Paint

There are two main categories of paint: water-based (latex), and oil-based (alkyds). Choosing one paint over the other can be tricky without a basic understanding of how they differ from each other. Here is a comparison to help you out.

Oil-Based Paint

Oil-based or alkyd paints consist of inorganic resins (pigments) suspended in a solvent. Commonly used solvents include linseed oil, mineral spirits (naphtha), toluene, xylene, and other petroleum distillate solvents. The term "alkyd" refers to the synthetic polyester resin that is used in the paint. A solvent such as turpentine or mineral spirits is typically used to modify the viscosity of oil-based paints. Oil base paints have very good adhesion, making them ideal for repainting a surface with heavy chalking. However, these paints tend to oxidize and get brittle, leading to chipping and cracking problems over time.



Water-Based Paint

Water-based paint or latex paint is a newer innovation than oil-based but it now accounts for nearly 80% of all paints sold today. It consists of a resin dissolved in water. At one time, the resin was exclusively latex (rubber) but many paints today use other materials such as vinyl or acrylic in place of latex so the "latex" designation may eventually disappear. A water-based paint can be easily thinned by adding water. Advantages of water-based paints include easy cleanup with soap and water, faster drying, fewer nasty fumes, and less likelihood of cracking.

Uses

Latex paint can be used on a wide variety of materials including wood, concrete, stucco, brick, galvanized metal, vinyl siding, aluminum siding, and drywall.

Oil-based paint can be used on many materials also, but for new concrete, stucco and other masonry, a sealer is required. It should also not be applied directly to galvanized metal. Oil-based paint is the better choice when repainting exterior surfaces with heavy chalking and exterior or interior surfaces with multiple layers of old oil-based paint. They also perform better when working with woods such as redwood and cedar which have water-soluble extractives that can bleed through latex paints.

Durability

Exterior water-based paints will generally outlast their oil-based counterparts as far as color retention, chalk resistance, and overall appearance. They also have less of a tendency to get brittle and form cracks because they are better able to expand and contract along with the surface to which they are applied (such as siding). For interior applications, the two types of paints have similar durability although oil-based paints are more susceptible to yellowing and chipping problems.

Drying Time

Oil-based paints take longer to dry than water-based ones - 24 hours or more is not uncommon. Latex paints dry much faster, typically in one to six hours. This is a decided advantage since a second coat can be applied without having to wait an entire day.

Safety

Oil-based paints are flammable and emit lots of fumes which can cause headaches, nausea, dizziness, and fatigue if you breath in the fumes for too long without good air circulation. In comparison, water-based paints are non-flammable, emit far less fumes, and clean up with just soap and water instead of harmful chemicals.