Dumping / sinking / collapsing of top coats

Loss of surface quality.

Sources of error:
- The substrate was not dried properly right into the underground.
- The material viscosity is too high. In this case, add a little more thinner.
- Incorrect thinning. Out of the system is often associated with trouble. Even though it is otherwise often practiced.
- The nozzle diameter is too small for the material used. Thicker material needs more space to „extract“ properly.
- Viscosity too thin – Lean spray pattern – Loss of gloss. Possibility of haze formation on the surface.
- Hardener and/or thinner have not been adapted to the temperature.
- Flash-off times have not been observed as specified.
- Inferior raw material. Those who buy „cheap“ often buy twice.
- Oxygen quantity in the drying process of the paint booth is too low. Some clear coats have problems with block heaters (BKHW).
- The layer thickness of the old paint is overcoated. A clean adequate result is in this case also void.
  More information on film thickness testing.
Error prevention:
- Process materials according to manufacturer’s specifications.
- Uniform coating. Varying coating thicknesses can make surfaces look like boggy material.
- Check nozzle size according to technical information and adjust if necessary. Excessively thin nozzles promote a lean spray pattern.
- Observe flash-off times between painting passes.
- Use higher quality material. „Cheap products“ are sometimes diluted with solvents, which also leads to shrinkage after the drying process. The solvent „floats“ in the material during the coating process. Afterward in the drying phase, it evaporates and you have a surface appearance as seen in the pictures.
Repair path:
- Sumped surfaces can be repaired by the well-known finish repair route (sanding – polishing), sometimes with great success.

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