It’s always a good idea to use the optimum material for any application, and this certainly applies to paints. Many factors influence the choice of paint, including the substrate being covered, condition and age of the substrate, its location and exposure to the elements. In this article, we’ll discuss the best uses of five different types of paints. We’ve discussed each of these paints in previous blogs, but today we’ll focus on when they should, and shouldn’t, be used.
Water based Paint
About 3/4 of the paint purchased by consumers is water based, often referred to as latex paint. It consists of a pigment, a water-soluble binder (usually acrylic) and water. The evaporation of the water allows the paint to dry and form a film. Modern latex paints offer excellent durability for interior and exterior surfaces. They dry quickly and clean up with soap and water. They can outlast oil-based paints and resist chalking, cracking, fading, blistering, flaking and peeling. Furthermore, they don’t have solvents that give off noxious volatile organic compounds (VOCs). Water-based paints are a good choice in most situations.
Oil based Paint
Oil-based paint has an organic binders and solvents, such as alkyds, that cure to a film finish. The have excellent adhesion, but can be problematic in exterior applications because they may yellow and turn brittle over time. Oil-based paint is used primarily for a few applications:
- To repaint exterior substrates that suffer from heavy chalking
- To repaint interior or exterior substrates that have four or more old layers of oil-based paint
- To paint interior trim, especially if you want a glossy surface
On the other hand, you should avoid oil-based paint when painting fresh masonry or galvanized iron — the paint will probably fail quickly on these substrates. Other drawbacks include longer drying time, difficult clean up and smelly VOCs.
Elastomeric paints are special exterior latex paints used on masonry surfaces. You apply them in thick coats (approximately 10 times as thick as regular paints) and they form a thick film. These paints are tough, flexible and stretch to accommodate expanding/contracting substrates. For this reason, you can use the paint to cover cracked surfaces, but cracks wider than 1/16 inch should first be caulked. Elastomeric paint is a popular covering for concrete and masonry, but should only be used on surfaces that will not become wet underneath the painted surface. These paints are fairly expensive and may chalk in sunny exposures — for this reason, they may not be available in dark tints.
This paint dries to a glossy, hard surface and is typically used to protect exterior surfaces. Enamel paints are usually oil-based, but latex versions are also available. They are often sold in spray cans that are useful for touch ups and small surfaces. It is commonly used to cover concrete surfaces and to render wood surfaces water-resistant. The enamel conveys good durability to its substrates. It’s also used to paint the surface of appliances, counters, and industrial or high-temperature equipment, such as a BBQ cooker or an engine.
Dual-component Paint (Epoxies and Urethanes)
Dual components paints are mixed just before use.
The two components in epoxy paints are a resin and a hardener. Epoxy paints provide tough, protective and hard coatings. They are extensively used to protect metal from corrosion and rusting. They resist heat, solvents, acids, alkalis and water, although they are vulnerable to chalking and yellowing from exposure to UV rays. There are many specialized epoxy coatings, including amines, polyamides, amidoamines, novolacs, siloxanes and epoxy esters.
Polyurethane paints are available in one- and two-part formulations. The dual component variety requires you to mix polyisocyanate with a polyol to form a polymerized coating that resists UV, water and wear. It is often used as a marine paint. It provides a semi-gloss or high-gloss finish. Polyurethane paints are commonly used to paint boats and cars.