Coatings Cafe
Edge
Defect Description
Edge defects happen when the paint flows unevenly from the sharp edge of a substrate. In the case of surface tension driven flow the paint can pull from the substrate edge leaving a lower film thickness at the sharp edge. In some applications the paint can build up on the edge and then form a small drip or sag. The drip effect is very strong as the film build increases beyond the sag tolerance film build for the paint.
Also known as: edge pull, poor edge coverage, sagging, drips,
Possible Causes of Defect
1. Film build is too high, especially clearcoat
2. Paint Viscosity is too low
3. Target Distance is too close
4. Booth balance for temperature and air flow
5. Check booth temperature and %humdity for waterborne coatings
Tips to Avoid Defect
-
1. Apply proper thickness -lower film thickness will sag less
2. Run with target paint viscosity at application temperature
3. Maintain proper gun distance
4. Maintain paint booth application process criteria
How to Repair the Defect?
- Consult your specific paint shop procedures.
- Finesse Deck: Sand plus 2-step Polish
- Spot Repair: Sand plus Repaint