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PROTECTING YOUR WORLD

Chemical Resistant
Coatings: Systems
Compared

Which coating chemistries hold up to acids, caustics, fuels and solvents, the difference between splash and immersion service, and how to spec a system that will not soften, blister or let go.
Chemical Coating Quotes

Acids, caustics or fuels? Get the right system.

Tell us what the surface sees and how often. We will connect you with a certified applicator who can match the coating to the chemical.

  • Chemicals and concentration
  • Splash, spill or immersion
  • Temperature of the service
  • Concrete or steel substrate
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Things that decide resistance: chemical, concentration, temperature
Manufacturer resistance charts
Splash
vs immersion: the first question in any chemical spec
Industry practice
D1308
ASTM spot and immersion test for household and lab chemicals
ASTM International
100%
Solids polyurea, no solvent to trap
Product data sheets

"Chemical resistant" on a can means very little until you know which chemical, how strong, how hot and for how long. A coating that shrugs off diesel drips can soften under hot caustic washdown, and one that survives sulfuric acid splash may fail in constant immersion. This guide explains how the main chemistries compare and how to specify one with the exposure spelled out, from a team that manufactures polyurea, polyurethane and hybrid coatings.

Quick answer

A chemical resistant coating is a protective lining chosen to resist a specific chemical at a specific concentration and temperature. For most acids, caustics and fuels in containment, sumps and floors, novolac epoxy and vinyl ester give the highest chemical resistance, while polyurea and polyurea hybrids give a thick, flexible, crack-bridging membrane that handles splash, spills and secondary containment with fast return to service. Always check the manufacturer chemical resistance chart for the exact chemical, and decide up front whether the service is splash, spill or immersion.

Start here

What makes a coating chemical resistant

Chemicals attack coatings in three ways: they dissolve or soften the resin, they permeate through the film and attack the substrate underneath, or they react with the coating and break it down. Dense, highly cross-linked films resist all three better, which is why novolac epoxies and vinyl esters top most resistance charts. Elastomers like polyurea trade a little chemical resistance for toughness, elongation and the ability to bridge cracks.

Chemical

Which chemical

Acids, caustics, solvents, fuels and oxidizers each attack resins differently. Name the actual product, not just "acid."

Strength

Concentration

10% sulfuric acid and 98% sulfuric acid are different services. Many coatings resist one and not the other.

Heat

Temperature

Resistance drops as temperature rises. A rating at 75°F says nothing about hot washdown or process spills.

Time

Exposure time

Splash cleaned up in hours is much easier than spills that sit for days or constant immersion.

Surface

Substrate

Steel, concrete and old coatings need different primers and prep. Concrete adds moisture and cracking to the list.

Cleaning

Cleaning and washdown

Hot water, caustic cleaners and pressure washing can be harder on a coating than the process chemical.

Read the chart the right wayManufacturer charts usually rate each chemical as recommended, splash or spill only, or not recommended, at a stated temperature. If your chemical or concentration is not listed, ask for test data or a patch test before you commit.
Compare

Chemical resistant coatings compared

SystemStrengthsWatch-outsBest fit
Standard epoxyGood resistance to many mild chemicals, fuels and oils; strong adhesionRigid; weaker against strong acids and solvents; chalks in sunlightLight-duty floors, mild spills
Novolac epoxyHigher resistance to strong acids, solvents and heat than standard epoxyBrittle; does not bridge moving cracks; needs good prepSumps, trenches, battery rooms, acid containment
Vinyl esterVery high resistance to strong acids and oxidizers, often glass-reinforcedOdor, shrinkage, skilled applicationSevere acid immersion, chemical plants
Spray polyureaThick seamless membrane, high elongation, cures in secondsCheck each chemical; some solvents and hot acids need other systemsSecondary containment, splash and spill zones, wastewater
Polyurea hybridLower cost, fast set, good water and spill resistanceLess chemical resistance than pure polyureaBudget containment, non-critical spill areas
PolyurethaneAbrasion resistant; aliphatic topcoats are UV stableMoisture sensitive during cureTopcoats over epoxy, floors with light chemicals
Typical behavior only. The product chemical resistance chart and data sheet govern.
Combine systemsMany specs pair a novolac or epoxy primer and base coat with a polyurea membrane for crack bridging, or put a chemical resistant topcoat over polyurea in a known-aggressive zone.
Where it goes

Chemical resistant coatings by area

Containment

Secondary containment

Dikes and berms around tanks need a seamless, crack-bridging liner that holds a spill until cleanup. See secondary containment.

Floors

Chemical plant and warehouse floors

Forklift traffic plus drips and spills. Choose for abrasion and chemistry together.

Sumps

Sumps, trenches and pits

Chemicals collect and sit here, so treat them as near-immersion service.

Wastewater

Wastewater and H2S

Hydrogen sulfide turns to sulfuric acid on concrete crowns. See wastewater coatings.

Tanks

Tank interiors

Immersion service needs a lining rated for that chemical and temperature. See tank lining.

Fuel

Fuel stations and truck bays

Diesel, gasoline and oils on concrete. See fuel tank liner.

Do it right

How to specify a chemical resistant coating

  1. List every chemical

    Product name, concentration and safety data sheet for each chemical, including cleaners and wash-down agents.

  2. Define the exposure

    Splash, spill (how long before cleanup), or immersion, plus the highest temperature it will see.

  3. Check the chart

    Confirm each chemical against the manufacturer chemical resistance chart at your temperature.

  4. Spec the prep

    Abrasive blast steel to the specified standard; shot blast or grind concrete and test moisture. See surface preparation.

  5. Spec thickness and system

    Primer, body coat and topcoat, with minimum dry film thickness for each.

  6. Test and document

    Holiday test linings, check thickness and adhesion, and keep the records.

Concrete moistureCoatings blister when moisture vapor pushes up from the slab. Test before coating and use a moisture-tolerant primer when needed.
Where we fit

When polyurea is the right call

Spray polyurea is 100% solids and gels in seconds, so an applicator can build a thick, seamless membrane on walls, floors and dikes in one visit. It stays flexible, so it bridges shrinkage cracks that would crack a rigid lining. It is a strong choice for secondary containment, spill zones and wastewater structures. It is not the answer to every chemical: strong solvents, hot concentrated acids and some oxidizers call for novolac epoxy, vinyl ester or a specialty lining.

  • Seamless: no laps or seams for a spill to find.
  • Crack bridging: high elongation moves with the concrete.
  • Fast return to service: walkable in minutes, not days.
  • Primer matters: specify a primer such as ArmorPrime for concrete and steel.

See our chemical coating products and the industrial coatings guide.

Chemical coatings

Match the coating to the chemical.

A certified ArmorThane applicator can review your chemical list and exposure and quote a system with prep, thickness and testing spelled out.

Contractors: become an ArmorThane applicator

FAQ

Chemical resistant coating questions

What is the most chemical resistant coating?

For strong acids and solvents, novolac epoxies and vinyl esters are usually the most chemical resistant coatings. The right answer depends on the exact chemical, concentration and temperature, so check the resistance chart.

Is polyurea chemical resistant?

Polyurea resists water, many dilute acids and caustics, fuels and oils, which suits secondary containment and spill areas. Some strong solvents and hot concentrated acids need a different system. Check the product chart for each chemical.

Is epoxy chemical resistant?

Standard epoxy resists many mild chemicals, oils and fuels. Novolac epoxy is the upgrade for stronger acids, solvents and higher temperatures.

What is the difference between splash and immersion resistance?

Splash means occasional contact that is cleaned up quickly. Immersion means the coating sits in the chemical continuously. Many coatings rated for splash are not rated for immersion.

How long does a chemical resistant coating last?

With the right chemistry, proper prep and the specified thickness, linings commonly last many years. Most early failures trace back to the wrong system for the exposure, poor prep or thin film.

AT
Written by the ArmorThane technical team. We have manufactured polyurea, polyurethane and polyaspartic coatings, spray foam and plural-component spray equipment in Springfield, Missouri since 1989. Chemical resistance varies by product; always follow the manufacturer chemical resistance chart and data sheet.

Sources

  1. ASTM D1308, effect of household chemicals on organic finishes. store.astm.org/d1308-20.html
  2. AMPP (formerly NACE and SSPC), coatings standards and training. ampp.org
  3. U.S. EPA, SPCC rule for oil spill prevention and containment. epa.gov/oil-spills-prevention-and-preparedness-regulations

Chemicals change the spec.

Owners get a certified ArmorThane applicator and a system matched to their chemicals. Contractors can add polyurea with our equipment and training, with no franchise fee and no royalties.

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