Pin holing

Causes:         11-_pin_holding.jpg
    – Application of a colored coat on top of ground coat that has been sprayed dry.
    – The air bubbles that form during the application because of high viscosity, low air
      pressure or because of high ambient temperature that lead to a very quick drying.
    – Old pinholes that were not sanded well.
    – Poor application of the putty.
    – Fiberglass bodies.
    – Insufficient mixing of polyesters.
    – Insufficient priming of polyesters.


Preventive measures:
    – Avoid spray dusting of the initial coats.
    – Use recommended viscosity (thinning ratios) and air pressure.
    – Sand well ground coats.
    – Use correct technique when applying putties.  Hold the knife at 60-degree
       angle in order to avoid rolling the putty and allowing the penetration of air bubbles.
    – Mix polyesters thoroughly.
    – Use polyester spray filler (574 with H353 hardener) whenever possible.
    – Ensure sufficient filling of polyesters.


    – Remove damaged finish.
    – Sand and apply polyester spray filler (574).
    – Prime and paint.


    You should never try to fill the holes with successive coats of primer filler.