Chemical resistant coatings protect from the harshest substances
Nearly all coatings will be exposed to chemicals at some point during their service, whether cleaning products, spills, or fumes. However most of these are mild, and the coating does not need a special formulation. Chemical resistant coatings or paints are designed to provide protection from the harshest of substances. They need to perform safely and consistently under punishing conditions, and so need to be highly resistant to a wide range of chemicals. Without proper protective coating, solvents, acids, alkalis, salts, and other substances can be absorbed by the substrate, causing deterioration and contamination.
The right chemical resistant coating is the one that satisfies the requirements of the chemical, as well as the needs of the substrate. Choosing correctly requires fully understanding both. In this article we will outline the different chemical resistant coatings types, and provide a guide for choosing the right one as well as where to find products and contractors in the States.
5 questions that help choose a chemical resistant coating
Substrates and environments which require heavy duty protection from chemicals include flooring, storage or holding tanks, pipelines, bunds, buried metal and concrete structures, treatment plants, laboratories, cooling towers, factories, machinery and equipment, just to name a few.
The range of substrates, environments, and chemicals is matched by the range of chemical resistant coatings. To choose the right chemical resistant coating you should answer the following questions:
- Which chemicals may be present?
Each coating has different strengths, and may provide protection from one chemical but not another.
- What is the concentration of the chemicals?
The strength of the chemical will obviously affect the coating’s resistance.
- What is the temperature of the chemical?
A heated chemical adds an extra factor for the coating to deal with.
- What is the degree of exposure to the chemical?
Will the substrate be immersed, or is it just contact exposure?
- How long does the exposure take?
How long will the coating need to withstand the chemical?
The 4 basic types of chemical resistant coatings
Chemical resistant coatings are available in a wide range of formulations, suited to different applications. The main types are polyurethane, epoxy, phenolic, and fluoropolymers. The choice of coating is further complicated by extra requirements such as high abrasion resistance, or sufficient lack of friction.
1. Epoxy coatings
Resistance: Epoxy coatings are a go-to for chemical resistance. They provide protection against acids, alkalis, solvents, caustic fluids, fuels, fatty acids, salt or sugar solutions, chemical cleaning detergents and more.
Uses: An unprotected concrete floor can quickly deteriorate through exposure to chemicals, particularly flooring in the food and drink industry, garages, factories, and plants. Having a floor that can withstand these exposures is important to prevent bacterial contamination. Epoxy coating is suitable for metals, concrete and wood.
Cons: The drawback with epoxy coatings is a tendency to weaken with high or fluctuating temperatures, and it is not as flexible as polyurethane. They are also not good with UV radiation (which causes it to chalk and fade), and can be stained by chemical attack.
2. Phenolic coatings
Resistance: These are the heavy duty chemical resistance coatings. A phenolic coating is one where a phenolic resin is used to cure an epoxy (as in the case of a phenolic epoxy) or a novolac. They resist 98% sulfuric acid, hydrochloric acid, transmission fluid, gasoline, formaldehyde, phenol, and numerous other chemicals. Perform well at higher temperatures than polyurethanes and epoxies.
Uses: Protective coating for tanks, ducts, piping, immersion service for most acids, solvents, and salts (chemical storage). Applicable for flooring in healthcare, science, technology and electronics industries, as well as chemical and waste treatment plants, pulp and paper mills, and power generation plants.
Cons: Not recommended for exposure to some strong organic acids and solvents, and the less epoxy used in the makeup of the coating, the less resistant to chemicals it is.
3. Fluoropolymer coatings
Resistance: Fluoropolymers are most known for being the non stick coating (including Xylan and Teflon). However, they also provide very high chemical resistance at high temperatures. They can withstand a maximum use temperature of 570°F. Fluoropolymers are resistant to a wide range of chemicals, including concentrated sulfuric, nitric, hydrochloric and phosphoric acids.
Uses: Normally used where a low coefficient of friction or a lubricious surface is required. Suitable for use on concrete or metal in secondary containment linings, acid plants, fertilizer plants, oil refineries, and more.
Cons: Fluoropolymers have poor weather protection characteristics, and cannot withstand acetone, esters, ketones, and acetic acid.
4. Polyurethane paints
Resistance: It is resistant to organic caustic fluids, acids and alkalis, fuel and hydraulic oils, and solvents.
Uses: Where greater flexibility and an ability to deal with high temperatures is needed, polyurethane is the traditional alternative to epoxy. Polyurethane is also the preferred choice in the dairy industry where there is exposure to lactic acids.
Cons: Softer than epoxy coatings, polyurethanes are more likely to abrade. Extremely sensitive to humidity at application. Less resistant than epoxies.
Find chemical resistant coating products, suppliers and services in the US
With so many different environments and surfaces that require chemical resistant coating, it is no surprise that the range of products and services is extensive. There are the coatings above, but there are also specially formulated coatings like methacrylate, which cures at low temperatures and is used for cold-store and freezer rooms. Below is a table outlining some of the available products. It is these coatings from reputable coatings manufacturers like AkzoNobel that installers trust.
|Chemical resistant coating type||Chemical resistant coating product||Product suitability|
|Two component epoxy||Jotun Jotafloor Topcoat||Ideal for industrial floors, laboratories, hospitals, food and beverage plants, kitchens, warehouses, factories, and manufacturing facilities.|
|Two component polyurethane topcoat||Rust-Oleum 9600 Rust-O-Thane Polyurethane||Heavy industrial and marine exposures, moist conditions and high abrasion and impact situations. Especially recommended for weather resistance.|
|Two component epoxy phenolic||International Interline 850||Tank and pipe lining for steel storage tanks and pipes containing a range of products including crude oil, gasoline, caustic solutions, potable water, and solvents.|
|Two component epoxy novolac||Sherwin-Williams Nova-Plate 325||For use on steel and masonry surfaces in industrial and marine environments such as oil storage tanks, secondary containment, ethanol storage tanks, and more.|
|Two component novolac vinyl ester||International Interline 955||Reinforced with glass flake to increase chemical and abrasion resistance. Intended for use in internal lining of chemical storage tanks and vessels for hot media (up to 195°F) or acids.|
Let us connect you with a chemical resistant coatings specialist
A chemical resistant coating should be applied by a trained professional to ensure an effective and flawless application. Fortunately there are many coating installer companies operating across the US. If you have a project that needs chemical resistant coating, our experts are here to help! In cooperation with our partners we can provide you with a tailor-made quote, and connect you with the right coating solution. Just get in touch via e-mail or the “Request a quote” button at the bottom of this article.