greatest concern to the facility. The VOC limit for
miscellaneous metal parts is 340 grams per liter (g/L) in most
parts of the country. This limit is the result of a 1978 Federal
EPA guideline for shop-applied coatings for metals (commonly
called miscellaneous metal parts) which 35 states adopted as part
of their state implementation plans for VOC control. Regulations
that limit the total amount of organic materials released into
the air by a coatings shop are also in effect in some areas of
the country. Architectural coatings are regulated in California
and some other regions of the country. In California, the
acceptable limits are based on the type of structure to be coated
(e.g., residential versus industrial) and coating type. For
example, for most coatings for residential use, the limit is 250
g/L and for steel in corrosive environments, the limit is usually
420 g/L. Some special use coatings have higher or unrestricted
VOC limits. Since these regulations are subject to change and
since they vary from region to region, a general listing of which
paints comply with local regulations is not presented.
3.2.1.3
Effect on Coatings. Traditional solvent-borne
coatings, such as alkyds and epoxies, have been reformulated to
meet the VOC regulations by using binders with lower viscosities,
modifying the solvents or using other techniques to lower the VOC
content. As examples, an epoxy, MIL-P-24441 has been
reformulated to have a VOC content less than 350 g/L. New lower
VOC content coating types have also been developed by using other
coating technologies such as waterborne or powder. VOC-induced
trends in coating selection are summarized below:
a)
Greater use of water-based paints
b)
Greater use of high-solids paints
c)
Less use of oil-based paints
d)
Elimination of lacquers (vinyls and chlorinated
rubbers)
e)
Increased use of powder coatings
In general, to obtain an acceptable service life, a
cleaner, better prepared surface is required for low-VOC content
coatings than for traditional higher VOC content coatings.
Application of low-VOC content field-applied coatings may also be
more difficult than higher VOC content coatings.
Problems have been encountered with the use of some
low-VOC content paints. They are summarized in Table 2.
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