A few examples taken from Fitz's Atlas 2 of Coating Defects
Alligatoring
Description
Very large (macro) crazing/cracking which resembles the skin of an alligator or crocodile. Cracks may penetrate through to the undercoat or down to the substrate.
Probable Cause
Internal stresses in the coating where the surface shrinks faster than the body of the paint film. Excessive film thickness and limited paint flexibility. Application of a hard topcoat over a more flexible softer undercoat. Application of topcoat before the undercoat has dried.
Prevention
Use correct coating specification and compatible materials. Avoid excessive film thickness. Avoid application at high ambient temperatures.
Repair
Repair will depend upon size and extent of alligatoring. Abrade or remove all affected coats and apply suitable undercoat and topcoat. Follow recommended application procedures.
Crazing
Description
Similar to checking but the cracks are generally wider and penetrate deeper into the film.
Probable Cause
Application temperature too low, incompatibility with previous coating, ageing and high film thickness.
Prevention
Apply a thinner coat of paint, add slower drying solvent, check application and drying conditions are correct for the paint system used and check compatibility.
Repair
Abrade and clean the surface and recoat.
Blistering - Osmotic
Description
Dome shaped projections or blisters in the dry paint film through local loss of adhesion from an underlying coating.
Probable Cause
Osmotic blistering is commonly associated with the presence of soluble salts, soluble pigments, soluble corrosion products, retained solvents or the absorption and retention of low molecular weight water miscible solvents, typically from the carriage of chemical cargoes.
Prevention
Ensure correct surface preparation and application and follow working procedures for ventilation etc. Apply a suitable coating system after testing for soluble salts. Consider the possibility of the different blister mechanisms in the particular environment.
Repair
Depending upon size and type of blistering, remove blistered areas or entire coating system, fresh water wash and repair or fully recoat.