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ARMORTHANE PROTECTING YOUR WORLD

PROTECTING YOUR WORLD

ARMORTHANE PROTECTING YOUR WORLD

Aromatic vs
Aliphatic Polyurea:
Which Do You Need?

The chemistry difference in plain English, how each behaves in sunlight, what each costs, and the aromatic-plus-aliphatic system most outdoor jobs use.
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MDI
Isocyanate behind aromatic polyurea
Polyurea chemistry
HDI / IPDI
Isocyanates behind aliphatic polyurea
Polyurea chemistry
Color shift
Aromatic darkens in UV, keeps its strength
Product data sheets
Top + base
Common outdoor system: aromatic + aliphatic
Industry practice

Every polyurea is made by reacting an isocyanate with an amine resin blend. Whether the isocyanate is aromatic or aliphatic changes how the coating handles sunlight, how much it costs and where it belongs. Most polyurea sprayed in the world is aromatic, because it is tough and economical. Aliphatic polyurea is the color-stable, UV-resistant version used where looks matter. We make both, and here is how to choose.

Quick answer

Aromatic polyurea is the tough, lower-cost workhorse used for linings, bedliners, containment, roofs and anything out of the sun, but it darkens and chalks under UV. Aliphatic polyurea holds its color and gloss outdoors and costs significantly more. Most exposed jobs use an aromatic polyurea body coat for thickness and toughness with a thin aliphatic polyurea or polyaspartic topcoat for UV stability.

What's in this guide
  1. 1What differs
  2. 2Combined system
  3. 3Polyaspartic
  4. 4Which to choose
  5. 5FAQ
Start here

What actually differs

The isocyanate side of the reaction defines the type. Aromatic isocyanates contain a benzene ring, which absorbs ultraviolet light and slowly oxidizes at the surface. That is why aromatic polyurea yellows, darkens and chalks in sunlight even while the bulk of the film keeps its strength. Aliphatic isocyanates have no aromatic ring, so they resist UV and hold color.

PropertyAromatic polyureaAliphatic polyurea
UV color stabilityDarkens and chalksHolds color and gloss
Physical toughnessExcellentExcellent; often harder
Typical use thicknessThick body coats, 40–125+ milsThin topcoats to full systems
Relative material costLowerSignificantly higher
Common usesLinings, bedliners, containment, roofs, coatings out of sunTopcoats, exposed decorative work, color-critical surfaces
Typical comparison; check specific product data sheets.
Best of both

The aromatic plus aliphatic system

  1. Prime

    Apply the primer specified for the substrate.

  2. Aromatic body coat

    Spray aromatic polyurea to the full specified thickness for toughness and waterproofing.

  3. Aliphatic topcoat

    Within the recoat window, apply an aliphatic polyurea or polyaspartic topcoat for UV and color stability.

Field noteRespect the recoat window. If the aromatic coat cures past it, scuff and prime before topcoating, or the topcoat can peel.
Related

Where polyaspartic fits

Polyaspartic coatings are a type of aliphatic polyurea made with aspartic ester amines that react more slowly. They can be rolled or sprayed with conventional equipment, are UV-stable, and are popular as floor coatings and topcoats. See polyurea vs polyaspartic.

Choose

Which polyurea for your job?

Aromatic

Out of the sun

Tank linings, secondary containment, below-grade waterproofing, interior floors under a topcoat.

Aromatic

Function over color

Bedliners, trailers and equipment where a darker color shift is acceptable.

Aromatic + aliphatic

Outdoors and visible

Roofs, decks and exposed equipment where color and reflectivity matter.

Aliphatic

Color-critical

Architectural and decorative finishes. See Highline 410 aliphatic polyurea.

More background in our polyurea guide and polyurea spray guide.

Polyurea systems

The right polyurea for the exposure.

Talk to a certified ArmorThane applicator about aromatic, aliphatic and combined systems for your project.

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FAQ

Aromatic vs aliphatic questions

What is the difference between aromatic and aliphatic polyurea?

The isocyanate used. Aromatic polyurea uses aromatic isocyanates such as MDI and changes color in sunlight; aliphatic polyurea uses aliphatic isocyanates such as HDI or IPDI and is UV and color stable.

Does aromatic polyurea lose strength in the sun?

The surface darkens and chalks, but the bulk of the film generally keeps its physical properties. Most outdoor systems still add an aliphatic topcoat for appearance and surface protection.

Why is aliphatic polyurea more expensive?

Aliphatic isocyanates and the resins used with them cost more to produce, so aliphatic polyurea typically costs significantly more per gallon.

Can you put aliphatic polyurea over aromatic polyurea?

Yes, that is the most common outdoor system. Apply the aliphatic topcoat within the recoat window or scuff and prime first.

Is polyaspartic aromatic or aliphatic?

Polyaspartic coatings are aliphatic, so they are UV stable.

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. Product selection should follow the specific product data sheets for your substrate and exposure.

Sources

  1. Polyurea Development Association resources. pda-online.org
  2. ASTM G154, fluorescent UV exposure testing of nonmetallic materials. astm.org

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