SELECTING EXTERIOR TOPCOATS BASED ON AESTHETIC PERFORMANCE

COATINGS & ULTRAVIOLET LIGHT

What is a Coating Polymer? • A carbon chain created primarily with by-products

of the petroleum industry. These polymers, also known as “resins”, provide the framework for which the coating’s performance is built upon

• Examples of a coating polymer include: ─ Epoxy ─ Urethane ─ Acrylic ─ Fluoropolymer

What Causes Coating Degradation? • Light Exposure

– Primarily Ultraviolet (UV) light, along with oxygen and water, can induce slow degradation (aging) of many organic polymers found in coatings

• Elements

─ Temperature fluctuations, pollution, chemical exposures, rain, etc. can also contribute to degradation, usually accelerating the process

Radiant Energy The Earth’s atmosphere filters and absorbs most of the more powerful shorter wavelength radiation, including UV light.

UV light harmlessly passes through film to the substrate

UV light is reflected from coating surface

Coatings absorb UV light but dissipate it as harmless heat

Transmission

Reflection

Absorption

Responses of Radiant Energy

Mechanisms of Coating Degradation • UV light absorbed by a coating excites the polymer,

raising the energy level that must be eliminated

• This energy breaks the primary polymer bonds, creating free radicals and begins a chain reaction of degradation if UV exposure continues

• Depending on resin type, once degradation begins, a rapid breakdown will occur

Increasing UV Resistance

• UV Resistant Binders

• Reflective Pigments

• UV Absorbing Pigments

• UV Inhibitors

PIGMENT SELECTION

Organic Pigments • Synthetic • Less color stable than inorganic • Bright organic colors are less

expensive than bright inorganic

Organic vs. Inorganic

Inorganic Pigments • Naturally occurring; metal based • Color stable • Less susceptible to free radicals • Bright colors are more expensive to

produce

Pigment Quality

• There are various grades of both inorganic and organic pigments

• Quality and performance can depend on: ─ Material make-up Carbon content Pigment color

─ Technology (organic vs. inorganic) Resistance to free radicals

EFFECTS OF ULTRAVIOLET LIGHT COLOR AND GLOSS

Ultraviolet Light (UV) on Color & Gloss • Damage caused by UV light can discolor

the binder, fade pigments and affect gloss

Acrylic Polyurethane

FEVE Fluoropolymer

Panel demonstrates coating performance after 10,000 hrs. QUV-A Exposure

Viewing Gloss

High gloss Low gloss

High gloss – Light is reflected causing coating to look brighter

Low gloss – Light is diffused causing coating to look duller

Viewing Color • Color, or color perception, can be greatly affected by a light

source or type

– Color indoors can be perceived much different than the same color outdoors

– Exact color and color differences can be determined using color equipment

– View color selection in same light source as exposure.

Comparing Color • Color and color differences can be

measured in Delta E (DE) in different ways: – CIELAB2000 – CMC – FMC II – Hunter

• Measurement scale should always be stated when comparing color

TOPCOAT SELECTION BASED ON GENERIC TYPE

Generic Coating Types • Epoxies

• Alkyds

• Acrylics

• Polyurethanes

• Polysiloxanes

• FEVE Fluoropolymers Control 6 Months Exp.

Waterbased Epoxy (black)

Epoxies

Control 6 Months Exp.

UV Light Performance • Poor UV stability Color • Yellowing of binder

• Fading of pigment • Chalking

Gloss • Extreme loss

These chemical and abrasion resistant coatings generally degrade in UV light due to absorption by a polymer chain in the binder. Epoxies are not recommended as topcoats when aesthetics are required.

Alkyds UV Light Performance • Poor to moderate

(depending on quality of oil)

Color • Some discoloration of binder Fading of pigments

• Chalking

Gloss • Will decrease at an accelerated rate

Alkyds’ convenient application make them widely used and can provide basic UV performance if comprised of quality materials.

Acrylics

While acrylic binder is not highly affected by UV, additives used to decrease cost and lower priced pigments can cause performance to decrease dramatically.

UV Light Performance • Good to very good Color • Little change to binder

• Possible fading of pigments Gloss • Moderate rate of loss

Aliphatic Polyurethanes

Binder is not highly affected by UV, but less costly additives and pigments can greatly affect performance. Generally provide good color and gloss retention.

UV Light Performance • Very good Color • Little change to binder

• Slow fading of pigments Gloss • Slow rate of loss

Polysiloxanes

Polysiloxanes typically utilize epoxy, acrylic or urethane binders. Those with acrylics and urethanes will outperform epoxy versions in both color and gloss.

UV Light Performance Very good Color Some yellowing of binder (epoxy)

Less potential fading of pigments

Gloss Slow rate of loss

FEVE Fluoropolymers

Fluoropolymers’ utilize binders that have a tenacious chemical bond, which are not highly affected by UV and typically use additives and pigments of high quality that do not affect color and gloss performance.

UV Light Performance Excellent Color Outstanding binder

Very good pigment tolerance to UV exposure

Gloss Extremely slow rate of loss

Life-Cycle Cost of Topcoat – Aesthetics Only 20 Year Life-Cycle of 30,000 FT2

Polymer Type

# of Applications

Years Between Touch-Up/Recoat

Service Life

Final Cost

Alkyd 5 3-4 Years 20 Years $ 230,625.00

Acrylic 3 4-6 Years 20 Years $ 140,625.00

Polyurethane 2 7-10 Years 20 Years $ 96,000.00

Polysiloxane 2 10-15 Years 20 Years $ 77,625.00

Fluoropolymer (FEVE) 1 15-20 Years 20 Years $ 71,250.00

Note: Figures listed are for topcoats only; they do not include primer and intermediate coat application and material costs.

OTHER CONSIDERATIONS COATING PERFORMANCE AND TESTING

Other Factors, Which Can Affect Aesthetics • Surface preparation • Coating compatibility

─ Complete coating system selection • Performance for specific environments • Application equipment & technique • Specification requirements

Writing Specifications • Write performance based specifications with standards and

minimum result requirements • Place coatings in Division 9: Section 09 96 00 High-

Performance Coatings • Utilize Division 9 “Sub-Sections” to better define the scope

of work & differentiate critical design elements • Seek assistance for side-by-side comparison of products

considered for substitution • Request slight, but noticeable variation in color between

intermediate coat and topcoat to ensure proper coverage.

• By incorporating performance standards into a specification, the owner is assured suitable, high-quality products − South Florida/Arizona exposures − AAMA (weathering standards only) − EMMAQUA: ASTM D 4141 − QUV: ASTM G 53 or ASTM D 4587 − Prohesion: ASTM G 85 − Salt Fog: ASTM B 117

Specifications

Exterior Testing

• Florida Exposure – Various angles to the sun – Extreme sun exposure – Salt air and spray

• Arizona Exposure ─ Intense Heat ─ Various exposure angles ─ Minimum cloud cover to

maximize radiation exposure ─ Dry harsh conditions

Real World Limitations • High-performance coating systems

could take 20 years before coating degradation

• Coating technology is dynamic and initial performance results are required quickly

Accelerated Testing

• UV Exposure • Sunlight Concentrator

– EMMAQUA • UV/Prohesion • Humidity

• Natural exposures can take years to obtain results

• Accelerated testing is utilized to emulate natural exposures with high concentrations of elements.

Accelerated Weathering • UV Exposure (QUV-A)

− Closely simulates natural sun − Cycles Include: 4 hours UV/4 hours condensation 8 hours UV/4 hours condensation

• EMMAQUA − Equatorial mount with mirrors and

water − Intensity of 8 suns − Tracks sun movement

Gloss Retention (White)— QUV Exposure (ASTM D 4587)

Color Change (White)— QUV Exposure (ASTM D 4587)

Importance of Systems

Unprimed 32 hrs.

Alkyd 500 hrs.

Epoxy 4,000 hrs.

Zinc-Rich Urethane 10,000 hrs.

Utilizing Results • Performance specification and minimum

results based on both laboratory and natural exposures

• Key Criteria ─ Color retention - Delta E (color space) ─ Gloss Retention (change from standard) ─ Chalking ─ Adhesion (system must remain in place)

• Retain sample panels • Product warranty required (outline acceptable

ranges)

CASE STUDIES EXTENDING PERFORMANCE WITH FEVE FLUOROPOLYMERS

Water Storage Tank Mt. Jackson, VA Finish Coat:

FEVE Fluoropolymer

OBSERVATION DECK PORT CANVERAL, FL

Finish Coat: FEVE Fluoropolymer

CAST IRON FAÇADE SALT LAKE CITY, UT

Finish Coat: FEVE Fluoropolymer (Metallic)

High Rise—New York, NY 12+ years of Performance (2002) Finish Coat:

FEVE Fluoropolymer (Metallic)

Important Points • UV light degrades coatings by activating free radicals in

binder, pigments and additives. • Various binders react differently to free radicals. Additives

can also be used to limit their effect. • Color and gloss retention depends on performance of binder,

pigments and additives. • High-performance coatings like FEVE Fluoropolymers, despite

being more expensive, provide longer-term aesthetic performance and lower life-cycle cost.

Thank you for your participation in today’s presentation. QUESTIONS?