Oil or Latex

Oil or Latex - What is in My Paint?

Many of our customers are interested in picking the most durable paint so the paint job will last longer without peeling, blistering, fading, or flaking.

When it come to exterior residential application, two factors stand out in determining paint's durability: film formation and the quality of the paint's ingredients.

Latex paints are comprised of tiny polymer and pigment particles dispersed in water. After applicaton, the water evaporates, leaving behind polymer particles that form a continuous thermoplastic film which is permeable to water vapors.

Oil paints, on the other hand, contain alkyd polymers that are dissolved (rather than dispersed) in petroleum-based thinner. After application the thinner evaporates, leaving behind a film which water vapors cannot penetrate. As a result, moisture trapped in the substrate may cause blistering and peeling.

Oil paints oxidize and embrittle with time, leading to cracking and flaking, making them adequate for less demanding environments, such as areas that experience little to moderate sunlight. Latex paints are more durable for use under more rugged conditions, where exposure to the sun's UV rays, moisture and temperature fluctuations exact a heavy toll.

Latex paints should not be applied when the temperatures fall below 50 degrees fahrenheit. Oil-based paints can be used down to 40 degrees.

The following ingredients extend the durability of latex paints:

An Acrylic Polymer Binder offers the best adhesion and durability.

A high percentage of solids (primarily pigments plus binder) form a thicker dry film. Cheaper paints contain more "extenders", such as clay and silica, and offer less durability despite high solid content.

Titanium Dioxide gives white and light colored paints their "hiding" power (also used in oils). Titanium levels may differ among top-quality paints because other ingredients are used to aid "hiding".

Ethylene Glycol (antifreeze) protects paint from occasional freezing.

Biocides protect paint in storage from possible spoiling due to bacterial growth, and mildew retardants fight mildew once the paint has been applied.

The paint manufacturing technology continues to evolve slowly. Many different brands are actually made in the same factory. In the last 6 years the industry has consolidated, and three Bay Area favorites were bought by national companies: Fuller O Brien and Sinclair (bought by ICI Corp.), and Anderson.

Brands without a strong local distribution network often command premium prices: Bengamin Moore and Pratt & Lambert are competitively priced in their local markets on the East Coast, but cost close to double in San Franciso. Nevertheless, many designers, contractors and home owners use boutique brands for their color selection and the superior service at small paint stores.

Since almost any premium product will perform equally well if applied correctly, the main factors related to brand selection are color selection, service, price, and availability.