12
Substrate
Mapping
The edge of the previous repair or putty is visible through the top layer of varnish - the outline of the repaired area appears on the surface as a subtle shadow or recess. Sometimes there are also visible scratches after grinding that have not been properly covered.
Cause
- Spray putty applied to unsuitable substrate - differences in surface tension cause edges to stand out
- Sanding the surface too smooth before applying the putty - the edges crumbled during sanding, leaving an uneven and jagged surface
- Repair site not properly sanded to the original paint system
- Area with filler not sanded to appropriate smoothness
- Improper sanding technique or poor sanding equipment
- Spray putty applied to the top layer of the old system instead of directly to the metal
- 1K filler used for larger recesses - shrinkage causes edges to stand out
- Poor or insufficient adhesion of the putty due to insufficient degreasing
- Application of paint products on soft finishes such as thermoplastic acrylics or insufficiently dried OEM systems
Prevention
- Before sanding, perform a diluent test - use the recommended system on a soft surface
- Degrease thoroughly before sanding
- Follow the correct sanding steps throughout the repair process - especially on jagged edges
- Use appropriate sanding blocks for smooth sanding
- Regularly check the surface of the filled area while sanding
- Thoroughly sand the repaired area back to the original paint system
- Spray putty only on stable surfaces
- Polyester putty only for filling small holes and scratches - not for large surfaces
Repair
- Sand the paint system thoroughly, including the problem area
- Repair the problem area using the appropriate system - spray filler, primer and topcoat
- Pay special attention to the edges of the repaired area - a gradual transition eliminates any marks