United Coatings Diathon® Roof Coating


Diathon® Roof Coating is an advanced acrylic elastomer coating that combines high solids emulsion polymers and potent biocides to provide superior durability, reflectivity, weatherproofing, and mildew resistance. Non-migrating fire retardant chemicals are permanently locked into the cured coating to assure performance. Diathon® Roof Coating is unique among acrylic elastomers in that elongation and tensile strength properties are both maintained at lower temperatures.

Sizes Available:

5 gallon (19 liter) pail
54 gallon (208 liter) drum

Colors Available:

White, Lt Tan, Lt Gray, Tan, Gray


Diathon® Roof Coating was specifically developed for protecting sprayed polyurethane foam insulation from degradation caused by normal weathering, aging and ultraviolet exposure. Diathon® Roof Coating has the unique property of being an elastomeric coating that is able to uniformly cover the profile of textured substrates. Diathon® Roof Coating is used for protection of sprayed polyurethane foam on new and existing roofs. Diathon® Roof Coating is available in standard White. White and Light Tan also meet California Title 24 requirements. If a faster drying white topcoat is desired, Diathon® Roof Coating is available in a Quick-Set version (Diathon® Roof Coating QS). The QS formulation provides a more rapid skin-over time than standard Diathon® Roof Coating, which helps to prevent wash-off from a light rain or dew in 30 to 60 minutes, depending upon ambient temperature & humidity. Diathon® Roof Coating is also available in a High-Tensile version (Diathon® Roof Coating HT), which provides approximately twice the tensile strength, tear strength and elongation properties.

Physical Properties

Solids by Weight 66% (±2) [ASTM D1644]
Solids by Volume 53% (±3) [ASTM D2697]
Tensile Strength 284 psi (±20) @ 75°F (24°C)
[ASTM D2370]
Elongation 258% (±20) @ 75°F (24°C)
[ASTM D2370]
*Diathon® Roof Coating is unique in that it
maintains its elongation values at freezing
temperatures, as well as after extended
Hardness 55-65 Shore A [ASTM D2240]
Permeance 22.5 U.S. Perms @ 20 mils (508
microns) [ASTM D1653]
Permeability 0.11 Perm Inches [ASTM E96]
ASTM D6083 Independently tested and certified to
exceed ASTM D6083 standards.
STAR® Program
Independently tested and certified
to surpass ENERGY STAR and CRRC
guidelines for energy efficiency.
High Temperature
Did not age-harden or slump at
temperatures up to 200°F (93°C).
[ASTM D794]
Retained After
After 1,000 hours exposure, passed
the requirements of ASTM D6083/
ASTM D2370 – minimum 100% @
73°F (23°C).
Bond Strength No adhesive failure between the
coating and PUF substrate. Diathon®
Roof Coating remained totally bonded
to the polyurethane foam under all
stress conditions. [ASTM C297]
Ponded Water
After 30 days of continuous testing,
Diathon® Roof Coating showed
no significant loss of adhesion. No
blistering or other deleterious effects
were observed.
VOC < 80 g />L
Dry Time for Foot
Traffic Resistance:*
3 hours at 75°F (24°C), 50% R.H.
Medium Gray @ 16 wet mils (406 microns)
5 hours at 75°F (24°C), 50% R.H.
White @ 16 wet mils (406 microns)
*Dry times will increase with lower
temperature and/or higher humidity.
Temperature Limits
for Normal Service
-30°F to 200°F (-35°C to 93°C)
Resistance to
After 3,000 hours of continuous
exposure, showed no deleterious
effects, no surface checking or
cracking, no delamination and no color
fade. [ASTM D6083, ASTM D4798]
Resistance to Wind
Driven Rain
After 40 hours of continuous testing,
no apparent moisture penetrated the
coating. [Tested in accordance with
Federal Specification TTC-555 B]
Resistance to
Foot Traffic
[Tested in accordance
with FM 4470]
No tearing, cracking, rupturing
or permanent deformation of the
Diathon® Roof Coating coating, or
exposure of the polyurethane foam
was observed.
Test exceeds the stresses of normal
roof maintenance traffic.
Low Temperature
Capable of withstanding 180° bends
over a 3/16” (5 mm) mandrel @ -21°F
(-30°C). [Federal Test Method no.
Cold Temperature
Flex after Weathering
After 1,000 hours exposure, retained
ability to withstand multiple ½”
(1.2 cm) mandrel bends without
cracking at -15°F (-18°C).
[ASTM D6083, ASTM D522]
Simulated Hail
[FM 4470 - Severe]
Coated foam panels passed multiple
impacts with no evidence of membrane
failure. Test was repeated following
1,000 hours exposure; no changes noted.


All documents are U.S. English unless otherwise noted

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