Installations and Assembly

Neither do the ANSI product emission standards
address characteristics of finishes and laminates, in
part due to the continually increasing variety of
finishes available. There are, however, increasing
numbers of governmental and non-governmental
organizations, and commercial purchasing
specifications that limit both formaldehyde and
VOC emissions from finished products such as
office and household furniture.
The importance of finishes and laminates in acting
as barriers to limit formaldehyde emissions from
unfinished products is widely recognized. For
example, in the German E1 guidelines, uncoated
wood panels must not exceed a specific
formaldehyde limit when the product is evaluated in
a Large Test Chamber. However, when unfinished
composite wood panels are destined to be finished
with a very specific list of coatings or laminates, the
substrate can meet a substantially higher emission
limit. All of the laminates and finishes recognized as
effective barriers in the German guidelines are also
discussed as barriers in this bulletin.
Mechanisms and Factors of Barriers
The effectiveness of an emission barrier is
determined by its basic permeability or porosity.
Other factors affecting a barrier’s effectiveness
include holes, cuts and the integrity of the laminate
or coating (see diagram).
Unbound VOCs escape through the surface of
the raw board during the aging process
Laminates or surface coatings restrict VOC
emissions
Emission barriers work by retarding the evaporation
and diffusion rates of VOCs. Evaporation and
diffusion are believed to be the primary release
mechanisms for VOCs that are not chemically
bound in the panel, such as solvents, adhesive
residues, and natural VOCs. For chemically bound
VOCs the mechanisms and factors are complex and
can involve sorption, mechanical/chemical/physical
processes, and decomposition related to hydrolysis
or heat, oxidation and chain breakdown resulting in
smaller and more volatile molecules.
It is generally well known that formaldehyde and
other VOC emissions from uncoated or
unlaminated products are dependent upon product
properties, indoor temperature and relative
humidity. Actual concentrations of VOCs in indoor
air, however, are functions of source loading ratio,
air exchange rate and finished product emission
rates, among others.
The decrease in VOC emissions from wood
composite panel products over time is called “decay.”
Published literature shows that the average half-life of
formaldehyde decay from newly manufactured
unfinished products, for example, is about 7 months.
Available data indicate that the same general
principles probably apply to at least some, if not
many other VOCs.
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“Barriers can provide
an effective means
of protecting the
substrate and
reduce potential
emissions by up
to 95%.”