| Microbiological degradation of
paint films - it's a micro-jungle out there: 
Paint degradation noted in humid exposure conditions
Increasingly, it has become evident that many materials can be degraded by
the presence and/or activities of microorganisms - paint coatings are no exception and
often contain biocides in an attempt to control such damage. By definition, microorganisms
are generally too small to be perceived by the unaided human eye.
Consider the following for in-service
paint coatings (microbial influenced deterioration is also a possible problem in uncured,
canned products):
Bacteria, fungi and algae have been reported to be of concern.
Algae photosynthesize their nutrients through sunlight and thus tend to be associated with
outdoor conditions. Fungi do not rely on sunlight in this manner and therefore tend to
also proliferate in indoor environments.
Mould (falls in the fungus category) growth on paint coatings can reduce
service life and degrade their appearance.
Different types of microorganisms can "support" each other
symbiotically (for example bacteria and moulds).
Moist, damp areas and relatively rough, dirty surfaces are generally
considered to be high risk areas.
As for other forms of life, moisture is considered vital to the growth of microorganisms.
Consider the words of Michael Finkel, describing a particularly barren stretch of the
Sahara desert in National Geographic Adventure: "Most parts, even bacteria can't
survive."
Microorganisms are ubiquitous - it is usually impossible to maintain
painted surfaces in a sterile condition and free of exposure to organism spores.
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References/Literature:
Resene Paints, Architects Memo, October 1998.
C.H. Hare: "Paint Film Degradation: Mechanisms and Control",
SSPC, 2001.
Links:
MIC in water systems at corrosion-club.com
(provides further details on microorganisms)
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