Paints and Coatings can be degraded by microorganisms.

Microbial contamination of paints and coatings can be divided into two main categories:

 

In can contamination

This is primarily a problem of aqueous based paints which results in spoilage prior to application of the paint. The paint becomes unuseable. Most aqueous paints contain preservatives to prevent growth but these can sometimes fail due to formulation incompatibilities or due to gross contamination in the production plant.

 

Film contamination

Microbes can attack a wide range of paints and coatings after application causing the failure of the protective properties and disfigurement and discolouration. The microbes may go on to cause corrosion or expose the coated surface to other forms of corrosion or deterioration. Excessive growth on internal painted surfaces can also result in a health hazard; microbial spores become suspended in the air where they may be inhaled causing allergenic reactions or infection.