
Pin-Holing or Bubbling
When tiny holes are produced on the finished surface, often arising from the substrate, the defect is called Pin-holing or Bubbling.
Possible Causes |
Solutions |
Atomized water in the air | Clean the air separator and drain water from the line |
Fine drops of moisture coming through the separator in the spray apparatus | Clean spraying equipment and purge the separator |
The open pore of wood has air trapped inside | Use a thin wash coat to penetrate the pore |
Production of fine bubbles after force drying |
• Use lengthened and recommended flash time, before drying. • Reduce the heat in the drying room. |
Bubbling of Carbon Dioxide from polyurethane causes pin pricks to appear |
• Happens when polyurethane reacts with moisture. • Use retarder and apply successive thinner coats. |
Drafts Causing Surface drying and forcing the solvent to break through the surface film and Evaporating to leave pin pricks | Avoid drafts, reduce viscosity or retard dry the material. |
Trapping of air by heavily viscous paint | Thin the paint |
Heavy film | Use thinner coats |