Installations and Assembly

Technical Bulletin Technical Bulletin Technical Bulletin Technical Bulletin Technical Bulletin Technical Bulletin Technical Bulletin
Copyright 2003
Composite
Panel Association
All rights reserved.
Reproduction in whole
or in part is prohibited
without prior express
written authorization
from CPA.
©
however, coatings of adequate thickness can be
effective barriers. Emission barrier effectiveness of
coatings may vary due to application; the type of
coating; environmental factors such as indoor
relative humidity and temperature; and substrate
characteristics. As well, cured coatings must exhibit
sufficient flexibility to retain integrity of the surface
during dimensional changes related to normal
humidity cycling.
Liquid applied coatings emit various VOCs and
some can emit formaldehyde. It should be noted
that concentrations are greater immediately
following application. Emissions from coatings
generally reach very low levels in a few hours or days
and can be less than 5% of the initial level in a few
days or weeks.
Two thin coats are generally much more effective as
an emission barrier than one thick coat and often
provide a more aesthetically pleasing surface. High
porosity areas on the surface of composite wood
panels can absorb enough of the initial coating to
cause breaks in the initial film. Subsequent coats
can mask and repair these breaks, reducing or
eliminating diffusion through the coating barrier
and improving its effectiveness.
The use of an integrated coating system for reducing
emissions in composite wood panel products has
achieved some success in arriving at functional
properties while reducing emissions. For example, a
system of polyurethane or alkyd as a base coat
minimizes grain raise and provides an emission
barrier. When combined with a compatible latex
topcoat, the VOC release potential of the coating
system is further reduced.
Surfacing Materials
Applying barriers, which consist of coatings or
laminates, on panel surfaces is one of the
approaches used to inhibit the release of VOCs
from particleboard and MDF products. Effective
barriers can reduce emissions by up to 95%.
Thick and Thin Laminates
Laminates are generally very effective as barriers to
emissions, thick laminates generally being more
effective than thin laminates. Thick laminates can
be either rigid or flexible and include the
following materials:
• High pressure laminates (HPL)
• Phenolic impregnated backer sheets
(20 mils+)
• vinyls (6 mils+)
When properly applied, thin laminates can be
effective barriers. Thin laminates include:
• Low pressure laminates (LPL)/Resin
saturated papers
• Thin vinyls (2-5 mils)
• Low basis weight papers
• Foils
Coatings
It is not the intention of this technical bulletin to
give comprehensive information on coatings as
emission barriers. When properly applied,