FIVE YEAR TEST:
Polyurethanes and Epoxies
over Plywood
The picture above shows two 3/4” (19 mm) exterior grade plywood panels
overcoated with different combinations of our polyurethane and
acrylic/epoxy coatings. There panels have been exposed to Seattle
weather continuously since Spring 2001, and were subjected to foot and
light automotive traffic.
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Test Notes:
Products used in these tests:
- Rhino Top, a water-based acrylic/epoxy exterior coating.
- Elastuff 120, a 2-part, 100% solids polyurethane coating.
- Uniflex 255 Aliphatic, a 2-part, elastomeric high-tensile finish/final coating.
- CPES™ (Clear Penetrating Epoxy Sealer)
- Dymonic® FC Sealant
- Fill-It™ Epoxy Filler
Before the panels were coated with our polyurethanes, all were primed
on top, bottom and edges with a single application of CPES, with the
exception of one panel end. CPES protects wood, and we wanted to
demonstrate this by not coating the end of one panel. The results can
be seen in pictures below.
CPES also provides a good bonding surface for our coatings, as well as
any other paint or clear coating. Coverage for CPES on good wood is
approximately 200-250 sq. ft. per gallon (5-6 sq. m. per l.).
The vertical ridges on the test panels are our Dymonic FC, a 100%
polyurethane sealant. The uneven horizontal ridge is Fill-It Epoxy
Filler. We wanted to also demonstrate the ability of our coatings to
bond with these products.
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Results (All test panels may be viewed in larger versions by clicking on the photo.)
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Left Side:
Rhino Top alone
over untreated
plywood.
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Right:
Rhino Top over
Elastuff 120 over
CPES treated plywood.
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On the left side of this test section is Rhino Top over the plywood
panel end that had not been treated with CPES. The plywood has rotted
and the Rhino Top cracked open. The first indication that this was
happening occurred after 24 months exposure. On the right side of the
test section is Rhino Top over Elastuff 120 on CPES coated plywood. The
surface is still intact with no signs of splitting or cracking.
Note the extensive fungal growth along the edge that did not receive
the CPES coating, and no fungal growth at all along the edge that was
coated with CPES. The edge of the CPES-treated panel remains firm and
unaffected by the exposure.
This is clear evidence of the ability of
CPES to protect wood. See our Plywood Preservation
Test for more
detailed information on the results of this test.
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Left: Elastuff 120
overcoated with
Rhino Top over
CPES treated plywood.
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Right:
Two Coats of
Elastuff 120 over
CPES treated plywood.
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On the right side the panel was coated with two layers of Elastuff 120
and left exposed. Exposure to weather and UV light has turned the
original gray surface to a creamy-tan color. This does not damage the
Elastuff coating, but the color is not particularly attractive. Note
that the surface shows no breaks or indication that the Elastuff is
delaminating from the surface. The small bubble rings occurred during
application as the wood displaced air into the coating. These are
hidden with any of our overcoatings, or can be sanded smooth after the
Elastuff cures.
On the left side the Elastuff 120 was coated with Rhino Top. The
surface is perfect. Bonding with the Dymonic FC polyurethane sealant is
intact.
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Left Side:
Two Coats of
Uniflex 255 over
CPES treated plywood.
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Right:
Three Coats of
Uniflex 255 over
CPES treated plywood.
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Left Side:
Two Coats of
Uniflex 255 over
CPES treated plywood.
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Right:
Two Coats of Uniflex 255
over Elastuff 120 on
CPES treated plywood.
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Uniflex 255 applied alone (with sand for non-skid purposes) over the
panel surface, two coats on the left and three coats on the right. Both
surfaces are perfect. The color is also as original (NOTE: Tile Red is
no longer available), with no indication of UV degradation. Vertical
ridge shows bonding with the Dymonic FC is intact and shows no wear,
and the same applies to the horizontal Fill-It ridge along the top.
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On the right the Uniflex 255 was applied over an Elastuff 120 base, and
on the left the Uniflex 255 alone. The Elastuff 120 provides a
smoother, more uniform surface, but both surfaces are intact and
without any signs of wear, deterioration or breaks. Bonding with the
Dymonic FC and the Fill-It is intact and also shows no signs of wear.
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The results of this long-term testing show the real-world durability
and inter-product compatibility of our line of polyurethane coatings,
caulks and epoxy fillers. They all bond together and they endure
outdoor exposure over a prolonged period of time. As the testing shows,
their endurance depends partly on the application of our CPES™ as a
wood protective coating.
How these products are used depends on the depth and level of
protection desired. Rhino Top alone over CPES-primed wood can be
regarded as a high quality paint. It will last for a several years and
then have to be recoated (click here for
complete info on Rhino Top).
It’s real value is as an overcoating for the Elastuff 120, where a
chemical bond is achieved between the Rhino Top and the Elastuff. As
the testing indicates, after 5 years of traffic and exposure there is
no sign that this combination is breaking down. The Elastuff/Rhino Top
makes an ideal deck coating, waterproof and durable.
The Elastuff 120 is also an ideal waterproof coating for boat hulls,
particularly from the waterline down. Its flexibility allows the wood
to expand and contract slightly without putting undue stress on the
wood joints and fasteners. If lightly sanded it can be over-painted
with any type of paint or coating. (Click
here for complete info on Elastuff 120).
Uniflex 255 Aliphatic is a thinner, easily applied polyurethane coating
that is waterproof and impervious to UV light. It is the ideal coating
for the UV protection of wood, and life expectancy exceeds 10 years. It
can also be used as a deck coating, and sand can be added for non-skid
traction (click here for complete info
on Uniflex).
Elastuff 120 overcoated with the Uniflex 255 Aliphatic is the ultimate
in tough, totally waterproof coatings. Click
here to see a schematic of
the polyurethane coating options, and their approximate cost per sq.
ft.
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Conclusions
1) All coatings that have been applied over a CPES treated surface
remain virtually as original after almost five years of extreme exposure.
2) Both the Fill-It Epoxy Filler and the Dymonic FC Sealant hold the
coatings and remain intact.
3) Wood that has not been protected by CPES will have a tendency to
rot, given the proper moisture and temperature. Wood that has been
treated with CPES is extremely resistant to rot.
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Recommendations
1) For durable, long-term surface protection for wood, use our
polyurethane coatings over a CPES treated
surface. These coatings will show the same durability when applied over
a properly prepared concrete, steel
or aluminum surface.
2) Use our Fill-It Epoxy Filler for filling and our Dymonic FC Sealant
for all sealing.
3) Treat plywood after it has been cut/trimmed with CPES. This will
significantly reduce the chance of rot
and delamination.
4) We recommend that you use standard exterior-grade untreated plywood,
and then treat it with CPES before installation. Pressure-treated
plywood is somewhat resistant to rot, but cutting treated plywood
exposes untreated wood, and it then becomes vulnerable.
For more details on CPES and Wood Preservation,
click here.
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