What Does Elastomeric Coating Mean?
Elastomeric coatings are protective barriers applied on interior and exterior walls as wall paints. Elastomeric coatings can be water-based coatings and paints or acrylic latex paints. They are applied as a thick coat on concrete structures.
Elastomeric coatings or acrylic resin coatings fall in the category of latex paints because they have a milky color when wet; and after drying they become flexible, stretchable and transparent.
An elastomeric coating may also be known as a latex coating or an acrylic latex.
Elastomeric coatings are best used for painting structures which require the kind of paint that forms a barrier against moisture. Although elastomeric paint is relatively new compared to many other paints, as it evolved—in the late 1950s—it has become one of the leading coatings used for many different types of structures.
Elastomeric coatings are typically used on exterior elements, such as concrete walls, roofs and floors. They should not be used on wood siding or logs that need to breathe, however, because any breach in the coating leads to moisture getting into the wood—which causes decay, mold growth and other damage. Wood should be allowed to properly dry and should not be sealed off until it is.
Corrosionpedia Explains Elastomeric Coating
A common application for elastomeric coatings is to prevent corrosion on steel reinforcement bars (called "rebars") by covering the gaps, cracks and small openings through which the outside air can enter. Elastomeric coatings also improve the structure's appearance.
Elastomeric coatings do the following:
- Block concrete's open pores when the coat dries.
- Resist solvents and microorganisms.
- Resist against chalking, cracking, blistering, peeling and flaking.
- Adhere strongly.
- Retain color for long periods.
- Dry quickly with minimal odor.
- Dry smooth when applied on surfaces.
The three most widely used types of elastomeric coatings are acrylic, silicone and urethane.
Acrylic Elastomeric Coatings
Acrylic elastomeric coatings water-based and usually only applied to roofs with a slope. If an acrylic roof has issues with water flow—meaning the water just sits and does not run off the roof—this can cause the coating to become diluted, turn back to a fluid and eventually wash off the roof.
By volume, acrylic elastomeric coatings make up about 52% solids and 48% water—which is why, at times, almost half the product is lost through evaporation when applied. They are, however, cheaper than many other elastomeric coatings—partially due to the fact that you’ll need to apply a lot more product to account for what gets lost during evaporation.
Silicone Elastomeric Coatings
Silicone elastomeric coatings are silicone resin-based coatings composed of 96% solids and 4% carrier—which means there is no danger of it washing away as an acrylic coating would.
This type of elastomeric coatings perform great on flat roofs because they can withstand sitting water. They are mid-range, in terms of performance and price, and are twice as resistant to weathering when compared to acrylics. However, they are more expensive than acrylic elastomeric coatings.
Urethane Elastomeric Coatings
Urethane elastomeric coatings are more impact-resistant than any other elastomeric coating available—although they are very expensive when compared to silicone and acrylic coatings.
Achieving Required Performance
To ensure elastomeric roof coatings perform as intended, it's important to ensure adequate film thickness. This is to protect from ultraviolet (UV) degradation, as coatings without adequate film thickness may not be able to sufficiently block UV rays and bridge cracks. When this happens, the color under the coating will start to show through; and if the coating has been applied to a dark surface, this can make the white coating appear gray.
As a general benchmark, elastomeric roof coatings can meet the physical properties specified in the technical data sheet (TDS) at a minimum of 20 dry film thickness (DFT).