Pin-Holing or Bubbling

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


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

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