Causes for Paint Failure

There are a number of reasons why a paint system may fail. These failures may be ascribed to any one of a number of causes and may therefore have a corresponding number of remedies. 

The following alphabetical listing of defects within the above four groups covers most of the causes for paint failure. There are still more reasons that can cause coatings to fail which are not included here [4]. 

Degeneration occurring in a coating during the passage of time and/or heating.  

Bleeding. Discoloration caused by migration of components from the underlying film. Substrates that can cause problems are those coated with tar- or bitumen-based materials, paints made on certain red and yellow organic pigments (which are partially soluble in solvent), some wallpapers, and timber stains that contain soluble dyes. The remedy is to use a specially formulated sealer or an aluminum paint. 

Blooming. The formation of a thin film on the surface of a paint film thereby causing the reduction of the luster or veiling its depth of color. This defect occurs mostly in stoving enamels (particularly blacks) in gas ovens. Lacquers also exhibit this defect, especially when used with low-quality thinners under certain ambient conditions. 

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Premature failure can also occur as a result of lack of attention to design. Facilities should, therefore, be provided for ventilatory drainage of water (rain, condensation, etc.), and all structures should be designed so as to permit ready access for repainting. Due consideration by architects and structural engineers at the design stage can indeed help to obviate certain of the causes of paint failure mentioned in this section (see also Sections 9.3 and 11.5). 

Unclean Surface. This is one of the most conunon causes of adhesive failure. Dust, dirt, loose scaly paint, oil, grease, etc. must be removed. Never clean with gasoline or fuel oils as they leave an oily residue. If you use solvents for cleaning, be careful to observe all rec-onunended safety precautions. 

Solvent resistance This varies from very poor (for chlorinated rubbers) to good (for polyurethanes). All paint binders have specific susceptibilities and the presence of small quantities of the appropriate solvent in the atmosphere in the region of an item of plant can cause rapid failure. 

A ballast tank filled with seawater is easily corroded. Corrosion protection by the paint on the metal surface inside the tank, which improves the insulation for the corrosion current, is conducted. The paint has problems with age-related degradation and incipient failure. To protect from the corrosion caused by these problems, plural sacrificial anodes are usually installed in the tank. When seawater is loaded in the tank, the surface of the inside tank becomes cathode and the protective potential works, because of the anode effects. The worse the coating condition becomes, the worse the insulation of the paint becomes and the lower the surface resistance becomes. Therefore, there is the possibility that the coating condition can be evaluated with the monitoring of the surface resistance. 

The research focused on accelerated effects of pollution on erosion, the normal degradative mechanism for a good paint system, and did not include catastrophic failures caused by loss of paint adhesion. The weight loss of specimens at low SO concentrations... 

As people concerned with such systems as paint, adhesives, and high-performance composites have long known, the effects of environmental exposure, especially to water, may be profound and deleterious. Water may plasticize the matrix and thus change its properties, or, as often happens, it may attack the substrate-matrix interface and cause failure (Halpin, 1969). Indeed, a major reason for the use of silane or other coupling agents on glass is to decrease the sensitivity to moisture (Bascom, 1969, 1970 Broutman and Krock, 1967, Chapters 6 and 13 Corten, 1966 Johannson et al, 1967 Kaas and Kardos, 1971 Plueddeman, 1970,1974 Plueddeman et al, 1962 Sterman and Marsden, 1966) for further details, see reviews by Bascom (1970, 1974). 

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