What are emulsion paints? Acrylic Paints? Water soluble Paints? Latex Paints?
Which types of paint are water based and which are oil based paints?
Oil based paints are also known as alkyd based paints, petroleum based paints, hydrocarbon based paints or solvent based paints. Water based paints comprise terms such as acrylic water based paint, latex paint, aqueous solvent based paint or water soluble emulsion paint.
For someone who is unfamiliar with the types of paint to use for walls, furniture, windows, gates and doors for home, choosing the right paint can be a challenge. Today, 90% of commercial paints available for home painting or commercial painting are water based paints. Painting contractors who once used oil based paints primarily for exterior painting & outdoor furniture painting have now switched to water based paints such as acrylic latex paints due to the improvisation and enhancement of emulsion paint composition and properties that are made to even suit external painting of not just masonry surfaces (walls & ceilings) but metal and wooden exterior frameworks such as gates, window grilles & metal roofs as well. With the new paint formulas, we remain the painting company that provides one of the most affordable painting services in Singapore.
Here is an overview of some of the paint properties that distinguish the two:
Elasticity
Oil based paint is generally harder than water based paints due to the solvent constitute in the mixture. The solvent component of a paint compound controls its quality in plastering consistency.
Water based paints contain water as solvent whereas oil based paints are either alkyd (synthetic resins) or hydrocarbon resins (petroleum) based. Water based paints such as latex or emulsion has greater flex and is able to withstand expansion movements due to its elastic property.
Oil based paint tend to crack over time due to wear and tear and temperature changes in the environment. This is especially so for homes that experience more drastic climatic changes with seasons. For an all year tropical weather like Singapore, oil based paints will be able to last longer without cracking not only due to constant weather, but also our relatively high humidity which keeps dryness of paint finish at bay.
In most houses, interior walls are being repeatedly painted over again and again as part of refurbishing or renovation works without first scraping off the underlying paint layer. If paint is being applied one layer on top of another, adhesion of the paint to the substrate will not be as good as compared to painting over a freshly stripped bare wall surface. This is especially so for oil based paint which tend to be brittle; and may result in cracks or peels on the wall paint easily.
Wearing
Oil based paint, or some know it as alkyd paint or petroleum based paint is generally harder wearing than water based latex acrylic paints or emulsion paints. Because of its hard wearing nature, it is most suitable to be applied on wood and metal and other hard surfaces. ICI Dulux Paint carries solvent-based paints known as enamels that are made to apply on metal surfaces. These oil paints are formulated to cater for various functional benefits such as anti-fungal and anti-bacteria.
How to paint with water based paint over oil based paint
If you are painting with acrylic water based paint over a surface that has previously been painted with oil based or alkyd resin paint, while it is possible to prime the substrate’s surface with a water based primer sealer or sand the surface down to improve bonding before applying water based paint over, the outcome may not be as durable as painting over with oil based paint. Oil based and water based paints do not mix and therefore would not adhere well with each other. If you have no other choice, invest in a good latex primer.
How to paint with oil based paint over water based paint
Likewise for using oil based paint over a surface previously painted with latex paint or any other water based paint. This often results in cracking or peeling of the new paint layer because water based paint being the undercoat has higher elasticity than the above lying oil based paint. Oil based paints are generally harder than water based paints as they are less flexible and less susceptible to temperature changes. The water based paint underneath will flex according to such changes while the top oil based paint does not, therefore it could only crack or warp with the underlying movements.
Appearance
Oil based paints generally give richer texture and finish due to the natural sheen in oil formulas. And because of its higher viscosity than water based paints, oil based paints provides better coverage and in hiding flaws. However now with improved formulas, water based paints can give as good masking qualities as oil based paints. With a variety of water based paints with glossy finish now available in the market, they too can produce rich enhancement on wall surfaces.
How to remove water based paint and oil based paint
If you opt for DIY painting, an important aspect you need to take note of would be the ease or hassle of cleaning up your painting tools such as paintbrushes after the job. Water based paints can be cleaned off from your painting brushes easily with just soap and water due to water solubility. If you are using oil based paint, you will need mineral spirits to wash them off, very often with more effort.
Drying and Curing
Although in general water based paints dry much faster than oil based paints, the drying time of paints depend on several factors. Weather such as temperature of the environment and humidity as well as the thickness & number of paint coatings will affect how fast the paint can dry. Paints tend to dry slower in cool temperatures and high humidity. In sunny and humid Singapore, always leave your fan on to speed up drying time. The drying time for water based paints take typically a few hours while oil based paints can only dry over 1 to 2 days. The labels of the paint cans you use should also state the estimated drying time of the paint. Do note that the drying process is not the same as curing.
Curing
Drying only means that the paint would not stain your fingers when you touch it as the water in the latex paint or water based paint, and the solvent in the case of oil based paint, has evaporated, leaving the paint to set when the resin binders and colour pigments amalgamate to form a layer of paint film. The colour of the paint you see at this point may not exactly be the same you see on the paint catalogues or paint swatches. The color will eventually surface upon the curing process. Curing takes up to a few weeks and is basically a process where oxidation of the applied paint takes place. When the paint is applied and exposed to air and oxygen and polymerizes the binding component, tightening the whole paint structure as the polymers bond together. This is when the inner or underlying layers of the paint and primer have all been completely dried.