Common Polyurea Application Issues & Solutions
- Blistering
Description:Bubbles of various sizes appear on the coating surface. When cut open, they contain air or voids.
Causes:
Substrate moisture content too high (>8%)
Primer not fully cured before spraying
Low temperature of A/B components causing ratio imbalance
High ambient humidity (>85%)
Solutions:
Test substrate moisture before application; if >8%, apply moisture barrier or dry the surface
Follow primer curing time strictly
Preheat materials to recommended temperature (usually 60–75°C)
Stop application when humidity exceeds 85%, or use dehumidification measures
- Pinholes
Description:Small needle-like holes on the surface, honeycomb-like, affecting waterproofing performance.
Causes:
Micro-pores in the substrate release air during spraying
Solutions:
Apply primer thoroughly to seal substrate pores
Use putty if necessary to close surface defects
3.Orange Peel
Description:Uneven texture similar to orange peel, affecting appearance and smoothness.
Causes:
Spray distance too far (>1.2 m)
Spray gun moving too slowly, causing material buildup
Solutions:
Keep spray distance at 0.8–1.0 m
Maintain consistent spray speed (0.5–0.8 m/s)
4.
- Foaming
Description: Sponge-like or foam structure with very low strength.
Causes:
Incorrect A/B ratio (excess prepolymer)
Moisture contamination causing reaction and CO₂ formation
Solutions:
Regularly check pumps and filters; test spray before application
Stop immediately if foaming occurs; clean and recalibrate equipment
Use materials promptly after opening; seal tightly to prevent moisture
Severely foamed coatings must be completely removed and reapplied.
- Delamination / Poor Adhesion
Description:Coating separates easily from substrate or between layers.
Causes:
Poor surface preparation (oil, dust, loose particles)
No primer or incompatible primer
Primer contaminated after long exposure
Excessive interval between layers
Solutions:
Ensure substrate is clean, dry, and solid
Use compatible primer
Apply Polyurea within recommended time (usually within 12 hours after primer touch-dry)
Control recoat interval; roughen surface if exceeded
- Sagging
Description:
Coating flows downward on vertical or inclined surfaces.
Causes:
Excessive thickness in one pass
Low temperature slows reaction
Solutions:
Apply in thin multiple layers
Adjust spray output and nozzle size
Increase ambient temperature if possible
- Cratering / Fish Eyes
Description:Round depressions exposing the substrate or primer.
Causes:
Surface contamination (oil, silicone, release agents)
Oil or water in compressed air system
Solutions:
Clean substrate with solvent before application
Ensure air compressor is equipped with oil-water separator and maintain regularly