Aliphatic vs. Aromatic Spray Systems

When it comes to discussing polyurethane or polyurea coatings, the terms “aliphatic” and “aromatic” are thrown into mix when spray systems come up in conversation.

The main difference between aliphatic and aromatic spray systems lies within their chemical structure, which influences performance, durability, UV stability and cost.

Chemical Structure

• Aromatic: Based on aromatic isocyanates, which contain benzene rings (e.g. MDI or TDI)

• Aliphatic: Based on aliphatic isocyanates, which DO NOT contain benzene rings, but possess open-chain structures instead. (e.g. HDI or IPDI)

  
  

UV Resistance

• Aromatic: Visually, aromatic systems have the tendency to change color and chalk when exposed to sunlight. A UV-stable topcoat can be applied to aromatic systems to improve UV stability if required.

• Aliphatic: Aliphatic systems offer excellent UV resistance and maintain color and gloss even with prolonged sun exposure. Aliphatic systems are recommended for outdoor applications.

  
  

Durability and Performance

• Aromatic:

  • Very tough and impact-resistant

  • Fast cure times

  • Commonly used in industrial and underground applications

• Aliphatic:

  • Excellent UV resistance with good mechanical properties

  • Superior aesthetic and weathering properties

  • Ideal for high-visibility or aesthetic applications

Cost

• Aromatic: More economical – widely used where UV resistance isn’t critical.

• Aliphatic: More expensive due to a complex chemistry and enhanced weathering resistance – but it’s more bang for your buck.

Typical Uses

• Aromatic:

  • High impact and abrasion applications

  • Waterproofing

  • Industrial tank coatings

• Aliphatic:

  • OEM applications

  • Cast applications requiring transparency

  • Decorative or high-visibility surfaces

Want to know what spray system is best for you? Give us a call.

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