Frequently Asked Questions


How green is Polyurea?

  • Once applied, polyurea is inert.
  • It should be disposed of as a solid.
  • No VOC’s and no solvents in the polyurea.
  • Primers contain solvents but the solvents flash off as the primer dries.
  • Curing time is therefore essential to ensure solvents do not become entrapped under the coating. This can lead to failure of the coating.

Curing time

  • 15 second initial cure versus 4-6 hour initial curing time for other systems.
  • At initial cure, 80% of the physical properties are present.
  • 24 hour full cure versus 7 day full cure for certain other systems. At full cure, full mechanical properties are present.
  • BENEFIT: Polyurea has a higher turnaround time.

Adhesion

  • The adhesion strength of the polyurea is stronger than the concrete breaking strength.

Storage

  • Polyurea may be stored at 25 degrees Celsius for a period of 6-9 months.

Discolouration

  • Polyureas are either ALIPHTIC or AROMATIC.
  • AROMATIC means the polyurea is UV resistant (does not break up). The colour may fade but the performance and stability is not affected.
  • ALIPHATIC means the polyurea is UV stable. It will not discolour and does not deteriorate due to UV exposure.

Why are all Polyureas not aliphatic

  • Aliphatic polyurea’s tend to be up to 3 x more expensive than their aromatic counterparts.
  • An aliphatic topcoat of 30 microns can be applied over aromatic polyurea. This is usually to achieve a desired colour.

Humidity / Temperature

  • Humidity does not affect polyurea application, and certain systems can be applied up to 80% humidity.
  • The surface preparation is however critical as any coating is only as good as the surface to which it is applied.
  • The substrate should not contain more than 1% moisture.

Pot life

  • A term applicable to castable polyureas (and paints).
  • Refers to the application time you have from mixing your components A & B.

Conditions of application area (Questions used to determine which system is best).

  • Exposure to chemicals.
  • Impact.
  • Temperature conditions.
  • Waterproofing properties required.

Standards

  • NUI Polyurea Systems are manufactured to DQS standards (European).
  • Testing to SABS standards which are in accordance with BS (British) and ASTM (American).

Aggregates

  • Silica sand/ glass beads/ ceramic beads.
  • Applied to high friction surface such as stairwells. Also gives a non-slip property.

Controlling for even thickness

  • This is monitored through consumption.
  • The operators spray technique is critical, and a good operator can monitor for consistent thickness.

Pigmentation

  • Applied polyurea is a creamy colour.
  • Pigment can be added to reach desired colour (2% non-reactive pigment). For specific colour, need the RAL number to match the colour.
  • Aliphatic topcoat is an option. Sprayed to 30 microns.
  • This topcoat must be applied before full cure is reached. This increases the wear of the topcoat.

Primers

  • Application thickness is generally between 50-100 microns.
  • Primers are pigmented ; one can therefore monitor coating thickness.
  • Different primers are different colours, thereby avoiding incorrect application on substrates eg concrete and steel primers are different colours.