Cracking
TRB0009
Cracking, (sometimes referred to as mudcracking), is the formation of cracks ranging from minute hair line sized which do not "break the surface" of the paint, all the way through to full cracking where wide fissures can be seen. Sometimes the primer coat can be seen thorough these fissures giving a duel colour effect.
22/09/2015 14:39:00
Causes
- Excessive film thickness of the topcoat
- Application of a topcoat over a primer that has been applied too thick or that is only superficially dry.
- Overall paint applied too thick.
- Insufficient or omitted hardener when mixing a 2k product.
- Use of paints incompatible with each other.
- Materials not uniformly mixed, (such as base and hardener).
Prevention
- Avoid excessive ‘piling on’ of topcoats.
- Ensure primers are mixed as per Technical Data Sheet and/or manufacturer’s instructions.
- Avoid excessive application of primer and topcoat.
- Avoid applying new paint to layers of old finish, if in doubt sand back to a safe film thickness or sand back to bare metal.
- Use correct hardener and mixing ratio.
- Make sure that the primer and topcoat are compatible with each other. If in doubt try a small area first.
- All paints should be stirred thoroughly before use.
Rectification
The areas effected must be sanded down to a smooth finish, or in severe cases where the cracking is especially deep removed to bare metal and repainted.