The failure of a paint system to hide or obliterate the colour of the original surface or the previous paint.

It may be caused by applying too few coats, using an undercoat of unsuitable colour, excessive spreading or uneven application of the paint.  It may also be caused through the use of poor quality paint.  Over thinning of paint and failure to incorporate settled pigments by thorough stirring are other possible causes.

To remedy the defect, it is necessary to apply further coats, avoiding any earlier faults in thinning, stirring or application.