Cracks of different length and width spread in various directions in the top coats.
CAUSES Normally cracking occurs due to wide fluctuation of temperature acting on the paint film build under the following conditions.
1. When the paint film build has too high a coat thickness.
2. Application of a repair finish over old paint-work which already contains barely visible hairline cracks.
3. Use of paint materials which are not designed to adapt to each others hardness or flexibility (e.g. a hard and rigid polyester stopper or filler, applied to a thermoplastic acrylic T.P.A. top coat, will lead to cracking due to the tensions caused by different expansion and contraction forces).
PREVENTION Only apply materials which are recommended for use with each other and keep to the film builds recommended by the manufacture.
REPAIR Sand down thoroughly until all traces of cracks are removed and repaint as required. Ensure that paint used to refinish area on flexible surfaces is treated with flexing agent (elastic-flex) additive.