EMSEAL has set the standard for
precompressed foam sealants.
Other than EMSEAL, there is
only one US-based manufacturer of precompressed foam sealants.
This other manufacturer while offering its own branded products also private-labels their isobutylene-and-wax-base
saturated products to all (nine (9) at last count) other US-based expansion joint
manufacturers who claim these products as their own.
This bulletin describes
why the performance of EMSEAL's 100% acrylic
impregnated precompressed foam sealant is different and unique. It
also offers simple testing procedures that validate these
claims and reveal the shortcomings of both wax and asphalt-based
The primary drivers of
the performance of EMSEAL's precompressed sealants are:
1) The incorporation of a 100% acrylic chemical emulsion into...
2) a high-grade open-cell polyurethane foam, and...
3) the use of 'impregnation' instead of 'saturation' in the relationship of
these component materials.
asphalt-compound impregnations as well as the wax-saturations of other
alternatives are not capable of the same performance as acrylic-based
Should you encounter
products being offered with the same performance claims, we would encourage
that these claims be tested and certified to the same performance conditions described in this bulletin.
We believe these performance
conditions to accurately reflect those expected to be experienced, or
reflect the designers expectations of performance, in applications for
which the materials are being specified and installed.
The following photographs
validate the performance claims of acrylic-impregnated, precompressed
sealants by comparing their claimed performance to the claimed performance
of a wax-saturated alternative under conditions simulating real-life
Figure 1: Acrylic-Impregnated
2-inch nominal acrylic-impregnated foam sealant
compressed to 1-inch
(-50% of movement claim),
heated to claimed
high-temp resistance of 185oF for 3-hours (to simulate mid-summer,
Southern exposure on a dark metal substrate).
1) The material compresses easily with acceptable force (11.32 psi) to the
minimum of published movement.
2) No bleeding (expulsion, melting, or leaching) of acrylic
wax-saturated foam sealant
compressed to 1-inch
(-50% of movement claim),
heated to 185oF for 3-hours (to simulate mid-summer,
Southern exposure on a dark metal substrate).
The material compresses with great difficulty requiring 35 psi force to
move the foam to the
minimum of published movement.
2) Bleeding (expulsion, melting, or leaching) of part of the wax
foam sealant relies for performance on a careful balance between the
properties of its cellular foam component and its chemical emulsion
chemical emulsion fills (in the case of saturation) or coats (in the case of
cells of the foam. The foam in turn provides the elastic memory that ensures an
inherent active backpressure. The amount of emulsion put into
the foam affects the degree to which the mechanical back-pressure of the
foam is dampened or deliberately restrained.
Some dampening is
essential to slow the expansion rate of the foam in order that the product
can be practically installed into a pre-constructed joint opening. Too
much dampening can negatively affect the product's ability to expand as the
joint opens when temperature drops.
Impregnation vs. Saturation:
Two philosophies have been employed in the production of precompressed foam
sealants--impregnation and saturation.
Impregnation is the process of using a controlled amount of
emulsion distributed over the cell walls of the foam. This
measured coating is designed to avoid choking the foam and over-dampening
it's spring-like elastic memory. To achieve watertightness in the foam
the use of an amount of impregnated foam that when compressed achieves a density
impermeable to water.
Saturation, by contrast, fills the foam cells completely and relies on less
foam but a greater amount of chemical emulsion to achieve a seal. This
approach has worked historically in some markets where climate and design
practice limits the movement range to which the product will be subjected.
Hybrid Precompressed Sealants:
In response to the need primarily in North America for materials with higher movement range, as well as
with market demands for colored seals, hybrid sealants were introduced by EMSEAL into the market in the early 1980's.
The hybridization involved
incorporating the dampened-spring feature of impregnated, precompressed foam
sealants with a factory cured silicone liquid sealant in the form of a
Asphalt, Wax, Acrylic--The Evolution:
Historically, the families from which chemical emulsions have
derived are asphalt, wax, and acrylic. The original invention in the
1950's was based on bitumen or asphalt. The patent for this invention
was circumvented in Europe through the use of a paraffin wax compound.
Both wax and asphalt suffer
similar shortcomings--low temperature brittleness and high temperature
Recognizing the ability of acrylics to extend the
low-temperature flexibility of asphalt as well as to simultaneously improve
high temperature stability, EMSEAL evolved its asphalt impregnations to
incorporate an acrylic component. This in turn lead towards the
development of first-generation 100% acrylic impregnations and ultimately to the latest in the evolution of precompressed foam sealant impregnation--microcell-modified,
hydrophobic acrylic impregnations.
Movement, Recovery, and Trade-Offs:
Because a large movement capability combined with high temperature stability
and low temperature flexibility are the overarching performance
requirements in high performance (100% total movement capable) sealants, it was realized by EMSEAL that it would not be possible (as
in its 50% movement capable COLORSEAL product) to achieve watertightness in
the foam backing while being able to accommodate the full range of movement
across achievable temperature conditions.
this reason EMSEAL has never claimed that the foam backing is performing a
waterproofing function in the 100% movement-capable SEISMIC COLORSEAL
product for example. Instead, the acrylic-impregnated foam provides:
support for the watertight silicone bellows;
b) thermal insulation in the
joint it is sealing;
c) a non-invasive anchoring mechanism;
d) the dampening mechanism by which the
material can be precompressed and practically inserted into the joint rather
than forced into the joint.
Claims of 100% movement
capability AND watertightness in the foam backing AS WELL AS high
temperature stability in combination with compression should be treated
SEISMIC COLORSEAL is a hybrid silicone-and-precompressed-impregnated
foam sealant. The silicone component is a factory-applied
bellows on the weathering face. The benchmark performance claims are:
Capability: 100% of nominal material size.
More explicitly this 100% is comprised of -50% compression AND +50%
extension from nominal size. This means,
for example, that 2" nominal material has the capability to be compressed to
1-inch and extend to 3-inches during the thermal cycling of a substrate.
and Substrate Suitability: These materials are offered for use in applications
involving porous substrates such as concrete, brick, stone, etc. and
non-porous substrates such as the metals used in curtain walls and metal
sealants are claimed to actively recover as the
result of the stored-strain energy of compression in the foam backing.
Typical descriptions include “back-pressure
inherent in the elastic open-cell foam backing.”,
and “works under its own
constant internal pressure”.
Stability and Resistance to Bleeding: High temperature stability
of 185°F (85°C) is typical.
By “stability” it is assumed that the chemical emulsion is
stable or will not melt, soften, or bleed from the foam matrix in which it
is retained. "Bleed” is assumed to mean the loss of the chemical
emulsion from the foam
matrix into or onto adjacent substrates or building materials.
Given that movement and temperature are related, it is reasonable to
test the related claims in unison.
Given that if specified and installed
into a condition that will utilize the full movement claim of the material,
it is reasonable to expect that the products can be compressed down 50% from
their nominal size and that this condition will occur during achievable high
temperatures on a building.
Actual substrate temperatures on dark-colored
substrates like bronze or black curtainwall mullions, on a Southerly
exposure, during the peak mid-day hours, in summer, are regularly recorded at
180o F (82o C). For purposes of this testing,
temperatures of 180o F (82o C), and 185o F (85oC)
Given that these products
claim the ability to follow joint opening movement through their inherent
backpressure, and that if specified and installed into a condition that will
utilize the full movement claim of the material, it is reasonable to expect
the material to recover unassisted from the compressed state achieved at the
claimed high temperature stability point to the maximum of its claimed
long pieces of 2-inch (50mm) nominal material are removed from their
shrink-wrap and hardboard packaging, and any mounting-adhesive release
liners are removed.
samples are installed between the faces of identical, aluminum, clamping
tightening the bolts in the clamping jigs, the samples
are compressed down to 1” (the -50%
movement claim. This dimension would be achieved in actual
applications during the heat of the summer as joints close due to the
expansion of adjacent structural materials).
samples are placed on a metal baking sheet, in a scientific oven, tilted at
an angle of 30 degrees.
samples are then baked
at 185-deg.F (85-deg.C) for 3 hours. (This temperature chosen to simulate a
south-facing, summer season, mid-day exposure on a dark-colored, metal
substrate like a window mullion).
the oven door is opened and the samples observed for signs of instability of the impregnation,
bleeding, and/or any change in the material. If bleeding has occurred,
the test is failed and discontiued.
samples are allowed to cool to room temperature.
clamping jig bolts are loosened
to allow the samples to recover. The recovery of the material over the next
3-24 hours observed.
As illustrated in the photographs above, under conditions achievable in
field applications, the the acrylic-impregnated
SEISMIC COLORSEAL material shows no evidence at all of bleeding, leaching,
or melting of acrylic impregnation either onto the substrates or out of the
temperature slowly drops to room temperature the substrates are moved slowly
apart. The acrylic-impregnated SEISMIC COLORSEAL begins immediately to
self-expand and the silicone bellows achieves expansion to 3-inches (75mm)
within 3 hours while the acrylic impregnated foam backing expands to beyond
While wax-compounds, like asphalt-compounds, can be formulated for as much as one-third the cost of
100% acrylic dispersions, by virtue of their inability to perform under
conditions reasonably determined to simulate real life conditions
they should not be considered viable alternatives to higher performing 100%
there remains a place in the market for low-movement, moderate-temperature applications for asphalt or wax-based products,
many of today's
construction environments and applications call for higher performance.
Regardless, manufacturers should be held accountable to prove their product
performance to the claims they make in data sheets.
Consequently, should you
be specifying an impregnated foam sealant product we suggest you require
proof of movement capability and temperature stability in combination, and
incorporate the following language in your specifications:
products to be certified in writing to be free, according to independent
and DSC, in composition
of any waxes or asphalts, wax compounds or asphalt compounds. All
substitute candidates shall be certified in writing to be:
a) capable of withstanding a minimum of 185°F (85°C) for 3 hours while compressed down to
the minimum of movement capability dimension of the basis of design product without evidence of any bleeding of
impregnation medium from the material; and b) that the same material after
the heat stability test, and after cooling to room temperature
68°F (20°C), will self-expand to the maximum of movement
capability claimed within 24 hours.
Independent Lab Certification--Wax Free
Fournier Transform Infrared Spectroscopy (FTIR) and Differential Scanning
Calorimetry (DSC) testing conducted by an independent laboratory is a simple
way to determine if the pre compressed foam sealant being considered
contains wax that might affect performance.
All of EMSEAL's foam
sealants are certified by independent laboratory to be free of wax or wax
Here to access the test reports. Demand the same of substitutes.
Request samples of any of the following acrylic-impregnated products from
EMSEAL and request the 'equals' from others.
Open, handle, and even
run these simples tests
to compare for yourself. We are confident you will agree that it is
possible to offer the best possible performance while delivering the best
value, custom made for your job, at
lead times that
respect your project schedule:
Once again, your
feedback as to the conditions of performance used to validate our claims, or
challenges to facts presented are invited. Please send them to
firstname.lastname@example.org. Thank you.
For complete guide
specifications for EMSEAL products, please go the individual product pages
at our Product and