Whats the Difference Between Oil and Water Based Paint?

Oil Based or Water Based Paint?

Determining which type of paint is most suitable for you and your paint project’s needs is an important step of completing your project, and it’s a bit more complicated than just getting a paint roller in your nearest paint shop. Check out the below information as we break down the difference between water and oil based paints, and help you determine what current coating is used in your house.

Oil-Based vs Water-Based: What’s the Difference?

When referring to whether a paint is oil or water based, we are actually talking about the type of solvent used in the paint, which is the liquid component of the paint that evaporates as the paint dries.  Oil-based paints (often incorrectly referred to as enamel) use an organic solvent in the makeup of the paint, which is typically a mineral turpentine. As the name suggests, the solvent used in a water-based paint (also known as acrylic paints) is almost all water.

Volatile Organic Compounds

A volatile organic compound (or VOC) is an organic solvent in vapour form. VOCs are the vapours and gases that are released as the organic solvent evaporates into the air, which is the drying process of paint. An organic solvent is made up of petrochemicals and plants, and expels vapours into the atmosphere as it evaporates. This vapour has a strong odour (that paint smell we all know!), is flammable and can have a harmful effect on the environment and human health. High exposure to these VOC’s can cause headaches, skin irritation and nausea for some people, which is why it is important to ensure there is good ventilation and air flow present when painting with an oil-based paint.

As water-based paints feature solvents that are primarily made up of water, they release much fewer VOCs into the air, and are therefore considered better for the environment and people’s health.

Characteristics of Oil-Based and Water-Based Paints

Sheen Levels

Oil-based paints can achieve a higher sheen level when applied due to the makeup of the paint; however, the sheen does become duller over time. While water-based paints achieve a lower sheen finish, water-based paints can typically maintain this sheen level over a longer period of time.

Durability

Typically, oil-based paints dry harder which provides excellent resistance to wear and tear.  However, as the paint dries harder there is not a lot of flexibility within the paint, which means oil-based paints are more likely to crack, become dry, brittle and chalky over time.  Oil-based paints are also known to yellow over time.  These days there have been many developments that allow water-based paints to dry quite hard and be effective when resisting damage and wear and tear. The flexibility afforded to water-based paints mean that they are able to expand and contract with weather conditions, making them less susceptible to cracking.

Exterior Use

Water-based paints perform brilliantly on exterior applications. This is because water-based paints are much more resistant to UV rays, allowing them to retain sheen levels and colour over long periods. The flexibility in the paint makeup means the paint can move with the substrate as is expends and contracts in different weather conditions, making it the perfect choice for exterior uses. Oil-based paint do not perform well in exterior conditions as it breaks down in UV light and develops a chalky surface. As there is little to no flexibility within the paint, the paint is not able to expand and contract with the substrate in differing weather conditions, making cracking more probable.

APPLICATION & CLEAN UP

WEATHER CONDITIONS

Water-based paints do not perform as well when applying paint in adverse weather conditions. Humidity and lower temperatures can extend drying times, whereas higher temperatures can cause the paint to dry too quickly. Water-based paints drying too quick or too slow can have an impact on the finished result, as well as the long-term performance of the paint.

Conversely, oil-based paints are much more tolerant of differing weather conditions, and therefore extreme temperatures and humidity do not have as large an impact on application, drying times and long-term paint performance.

Surface Conditions

Water-based paints can tolerate small amounts of moisture on a surface prior to application, as the paint is able to absorb the moisture. This will thin the paint out ever so slightly, but will not affect the paint’s ability to create an adhesion bond to the surface.

As oil-based paints repel water, the paint is unable to create a strong adhesion bond to the surface. As a result, any substrate that oil-based paint is applied to must be completely dry before application.

Application

Oil-based paints are typically slower to apply than water-based paints, as the paint has a stickier and thicker feel to it.  During the painting process, oil-based paints are responsible for the emission of high VOCs, which creates that strong “new paint smell”. As water-based paints contain substantially less VOCs, the smell after painting is not as strong.

Drying times are also vastly different, depending on the type of paint you select:

CLEAN UP

Water-based paints are much easier to clean up due to the solvent being mainly water, and brushes and painting accessories can by typically cleaned with water. Oil-based paints require turps or other specialty thinners to be used in the clean-up process.

Do I have water-based or oil-based paint in my house?

The test to determine whether your paint is oil-based or water-based is pretty easy. Simply put some methylated spirits on a rag and wipe at a small section of your wall. If the cloth is stained with the wall colour, it is water-based.

If you wish to repaint your existing oil-based wall with a water-based paint, sand back the wall with sandpaper to remove the sheen. Apply an undercoat to the substrate, allow to dry and coat with your new water-based paint.

Time to talk to the pros!

Before you start your next project, we recommend you head into your nearest Inspirations Paint store to have to have a chat to the experts before you start your next paint project. They will be able to answer any questions that you might have, and be able to give advice on choosing the right paint for your project!