Introduction to Coatings - · PDF fileIntroduction to Coatings: ... • Summary Comparison...
Transcript of Introduction to Coatings - · PDF fileIntroduction to Coatings: ... • Summary Comparison...
Introduction to Coatings Field Performance and the Application Process
Linetec is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request.
This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
Learning Objectives
Participants of this course will learn how different paint and anodize finishes rate when compared to architectural specifications. Participants will also learn about the application process to assure a quality product is provided.
Length: 1 hour
Credits: 1 LU/HSW
Copyright Materials
This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of
the speaker is prohibited.
Introduction to Coatings: Field Performance and the Application Process • The Anodizing Process
• Anodize Specifications and Performance
• The Paint Process
• Paint Specifications and Performance
• The Powder Coat Process
• Summary Comparison of all Coating Types
The Anodize Process
What is Anodizing? Anodizing is the process of electrochemically controlling, accelerating and enhancing oxidation of an aluminum substrate.
Oxidation naturally results from the exposure of a metal substrate to oxygen. During oxidation, the outside layer of metal is converted to a porous layer of metal and oxygen (an oxide film). This natural oxide film offers minimal protection for the aluminum substrate.
The anodizing process produces an oxide film that is uniform, hard and protects the rest of the aluminum substrate from deterioration. Electricity Chemicals
Aluminum
Aluminum Oxide Coating
Aluminum
Barrier Layer
Anodic Pore
The anodizing process thickens the natural oxide film resulting in a heavy aluminum oxide film of controlled thickness having the hardness similar to that of a sapphire (second hardest substance known to man).
Aluminum Oxide Layer
Oxide Film Structure
Anodize Performance • Avoids aluminum deterioration
• Extremely hard coating
• Similar to sapphire, second hardest substance on earth
• Semi-transparent coating
Anodizing – Multi-Stage Process
• Racking
• Cleaning
• Etching
• Anodize
• Coloring
• Seal Process
Anodize Line
A sophisticated computerized hoist system guides material through the anodize process
Anodize Process Racking There are several steps in the anodize process. Each step is critical to insure a quality product. The first step is racking the material. Material is clamped or welded to a rack so electrical contact can be made. Contact is critical to ensure mill thickness and tight color match.
Weld Racking
Typically used for stock length extrusions
Clamp Racking
Typically used for cut to size and fabricated pieces
Fixture Racking
Typically used for large volume, identical parts
Anodizing Process – Cleaning • Alkaline Cleaner
• Removes dirt, water, oils from aluminum surface • Cleaning process does not remove grease or marker ink
Anodizing Process – Cleaning • After racking, the anodize process begins with the material
being cleaned in a non-etching alkaline chemical cleaner to remove all shop dirt, water, soluble oils, etc., which may have accumulated on the material during handling and/or manufacturing.
• After cleaning, the material is ready for the etch tank. The etch process will produce a matte finish and also minimize minor surface imperfections such as light die lines and minor travel marks. Etching will not eliminate ALL surface imperfections.
• Next, the material is desmutted and rinsed to remove residuals left from the etch. This is the final preparation stage prior to anodizing
Anodizing Process – Etching • Immersed in caustic or acid (eco-friendly) bath
• Produces a “matte” finish
• Removed minor scratches and minor die lines
• Will not remove all surface defects
• Etch quality is critical to final appearance because anodize is a semi-transparent coating
• Hides small defects in the aluminum surface, allowing for anodizing of recycled/secondary billet
• Provides a frostier, matte finish
• Lower gloss level, reducing sunlight glare
• Aluminum removed during etch process is reduced by 80%, down to 0.5 mils
• Has the viscosity of water and less likely to collect in small recesses of aluminum extrusions
Eco-Friendly Etch Process
Anodizing Process – Anodic Coating • Immersed in 15% sulfuric acid
• Charged with electrical dc current
• Aluminum oxide layer formed • known as clear or satin
• The longer the immersion time, the thicker the coating
Clear Anodize
Anodizing Process – Coloring If the material requires coloring it is moved to an electrolytic two-step coloring tank. Tin metal is electrochemically introduced into the anodic pores to produce bronze tones from light champagne to black. Parts are immersed into an optional color tank to achieve champagne to bronze-tones to black. The amount of time the part is immersed will determine the color achieved. Darker colors are created by extending the immersion time and increasing metal deposition. In the industry, this is known as “electrolytic color” or “2-step color”
Anodizing Process – Electrolytic or Two-Step Coloring
Aluminum Substrate
Anodic Pore
Tin Deposit
Note that tin is deposited at the bottom of the anodic pore. The intensity of the color depends on the amount of tin deposited
Anodizing Process – Coloring • Champagne, bronze tones, black
• Known as “electrolytic color” or “two-step color”
• All colors in a single tank
• Color dependent on the amount of tin deposited
• Alloy and temper of the aluminum also can affect color
• Amount of tin deposited depends on the time in the tank
• Lightest colors are the toughest to control
Color created by electro-deposition of tin
Anodizing Process – Seal (closing of the pores) • After etching, anodizing and coloring, the aluminum
material is iImmersed in a high purity hydrothermal solution
• Protects anodic coating and coloring from weathering
• Closes and seals the anodic pores
The proper sealing is absolutely essential to the satisfactory performance of the coating. The pores must be rendered nonabsorbent to provide maximum resistance to corrosion and stains. This is accomplished through a hydrothermal treatment in proprietary chemical baths
Anodizing Process – Quality Control Analysis A computer automated
system controls and monitors product through the entire anodizing process. It tracks all aspects of the process including tank sequencing, time , temperature, voltage, current, etc. Anodize color is checked visually with prepared range samples. Each color has a unique set of samples with light and dark range limits.
Anodizing Process – Quality Control Analysis
Champagne anodize range samples
Dark bronze anodize range samples
Anodizing Process – Quality Control Tests • Color
• Visual test to range samples
• Spectrophotometeter (no recommended)
• Coating Thickness • Isoscope
• Chemistry • Autotitrator
Anodizing Specifications and Performance
AAMA Anodizing Specification Spec Number: AAMA 611-12
Class I Class II
End Use Exterior Interior or exterior w/regular maintenance
Film Thickness 0.7 mils 0.4 mils
Salt Spray Resistance
3000 hours 1000 hours
Color Retention 5 yrs: Fade = 5 Delta E 5 yrs: Fade = 5 Delta E
Class I Anodize is used on the exterior of architectural projects. It has a higher mil thickness than Class II anodize, it is more resistant to salt spray and the sea coast, and it is more durable in high traffic areas. Class II anodize is typically used on light commercial or the interior of a structure. It can be used on the exterior but it is not as durable or wear resistant as Class I anodize. No warranty is offered for Class II anodize.
Industry Product “Labels” Two-step color Class I
Champagne
Light Bronze
Medium Bronze
Dark Bronze
Extra-dark Bronze
Black
Class I Class II Clear 215R1 204R1
Strengths of Anodize • Durability, abrasion resistance
• Metal appearance
• Excellent weatherability (Class I)
The first illustration shows the anodized aluminum scratched multiple times by a nickel. The second images shows the aluminum after being wiped with a wet cloth. The scratch residue comes right off and the aluminum is completely unharmed.
Limitations of Anodize
• Limited color choice
• Will not hide surface defects on aluminum (caustic etch process)
• Finish will vary depending on alloy of the aluminum
• Difficult to match anodized sheet with anodized extrusions
• Strong acids/alkalis will quickly deteriorate the aluminum anodized surface
• Field repair is difficult at best, and sometimes not possible
• Chemical attack from acid or alkaline materials - most common occurrence is encountered when mortar or muriatic acid is allowed to dwell, even for a short time
The following limitations of anodize aluminum must be considered when selecting a high-performance aluminum finish.
Points to Specify for an Anodized Finish • Refer to AAMA 611-12
• Class I or Class II
• Color – state “two-step electrolytic”
• Color consistency range <5 delta E
• Eco-friendly (acid) etch process • creates an aesthetically appealing "frostier" appearance that helps hide small
defects in the aluminum
The Painting Process
What is Painting? • Painting is the application of a protective,
decorative organic coating to the surface of a substrate • Spray Coating Method
• Horizontal paint line • Vertical paint line
• Coil Coating Method
Painting Multi-Step Process
• Racking
• Pretreatment
• Painting
• Curing
• Quality Assurance
Racking All parts have unique racking methods based on the exposure of the material. Racking is a critical step in the process to ensure the automated spray bells and the painters can get good coverage in all exposed areas.
Pretreatment Process
The second stage in the painting process is the pretreatment. This step is very critical for corrosion and adhesion. Paint systems are designed to be applied over clean metal that has been properly pretreated. Pretreatment consists of 3 basic stages
Cleaning – alkaline or acid base cleaner which removes water soluable oils, dirt, etc…
Chromium Phosphate Coating – is added to the aluminum surface to increase the corrosion resistance, adherence and durability of any applied paint film
Rinse – the final stage of pretreatment is a high-power clean water rinse
Pretreatment Process • Multistage Process
• Cleaning • Remove surface contaminants, water
soluble oil
• Conversion Coating • Ensures adhesion of the paint
• Adds corrosion protection
• Chrome or chrome-free
Pretreatment Process
Chromium phosphate and chrome-free coating meet the AAMA 2605 high-performance standard of pretreatment.
Paint Application
Paint can be applied using a variety of methods - Hand spray – person in a booth painting the material - Automatic spray equipment – provides the best flexibility, efficiency, and consistent quality possible Most painters use a combination of automatic equipment and hand sprayers
Paint Application Illustration of a complete paint system, outlining the application of primer, pant, and clear coat. Note that not all paints require a primer coat or a clear coat.
Automatic Spray Bells
Rotary atomization bells, allowing for best flexibility, efficiency and quality possible, serve as the primary paint applicators in most production settings
Hand Spray Reinforcement
Although automatic spray bells can ensure coverage on the majority of parts, manual spray reinforcement is still necessary at times. Automated lifts allow the painters to move up and down, to ensure all areas of the parts can be reached.
Paint Line in action
Paint Cure Process There are several methods to cure painted material, most architectural paints are cured by baking in a convection oven. For proper cure 50% and 70% fluoropolymer (Kynar 500®/ Hylar 5000®) finishes the aluminum must reach a peak metal temperature (PMT) of 450 degrees Fahrenheit for at least five minutes. When applying baked enamel paints, the aluminum must reach a peak temperature of 350 degrees. Precision of cure is important for consistent color and gloss
Pigment and Resin left on the Substrate Resin surrounds pigment particles binding them to the substrate Solvent escapes
during baking
Primer
Substrate
During the curing process solvents escape from the paint. The cured resin and pigment remains on the surface of the part. Most architectural paints cure at a temperature of 350° to 450° Fahrenheit
Quality Control Tests • Mil thickness
• Color
• Gloss
Quality Control Tests
Spectrophotometers
This instrument measures color. This is done to ensure the project material matches the approved color standard.
BYK-Gardner Color-Guide™ Gloss
This unique instrument simultaneously measures
color and gloss to make sure the material meets
the specification.
Quality Control Tests
Test panels can be run with project material. The AAMA specification tests are then done on these sample panels to assure a quality product. The test results should be kept on file so they can be referenced in the event of a job site issue.
Some of the tests done are:
•Impact Resistance
•Adhesion (Boiling Water)
•Mortar Resistance
•Acid Resistance
•Mil Thickness
•Pencil Hardness
Test Panels
Job Panels are sent to South Florida for weathering tests
70% Fluoropolymer paint panels cannot fade more than 5 Delta E’s in a period of 10 years, and they cannot chalk more than a rating of 8 in a 10 year period.
These are critical factors to assure a long-lasting and maintenance free finish on architectural products.
Environmental Considerations of Paint • Solvent Vapors (VOC)
• Should be sprayed and cured in a 100% enclosed capture area
• Routed to, and destroyed by, a thermal oxidizer
In order to be Environmentally Friendly, finishers need to destroy VOC’s (solvent vapors). This is done with a thermal oxidizer as shown. The thermal oxidizer burns the solvents, turning them into carbon dioxide and water vapor before emitting them into the atmosphere.
Environmental Considerations of Paint • Landfill Waste Reduction
• Applicator should have wastewater recovery system to minimize waste chrome
• Remove all paint-related waste from landfill by fuel-blending and reusing as heat energy
• Utilize paint solvent recycle program
Paint Specifications and Performance
AAMA 2603
South Florida Weathering
Color Retention 1 year – slight fade
Chalk Retention 1 year – slight chalk
Gloss Retention No specification
Erosion Resistance No specification
Dry Film Thickness 0.8 mils minimum
Pretreatment System Chrome or Chrome Free
Accelerated Testing
Salt Spray 1,500 hours
Humidity 1,500 hours
AAMA 2603 Paint Specification
AAMA 2603 is typically an Interior Specification. Baked Enamel paints meet the AAMA 2603 spec.
The baked enamel coatings are harder than the PVDF (Fluoropolymer) coatings and are used quite often for interior application where color retention is not required. These paints are less expensive than PVDF paints, but once again, have poor resistance to color fading and chalking.
AAMA 2603 – Baked Enamel Coatings • Attributes
• Very good hardness
• Achieves AAMA 2603 (only)
• Low cost
• Limitations • Poor color and gloss retention
• Fair chemical resistance
• Applications • Interior products
Baked Enamel Systems Manufacturer Trade Names
• Akzo Nobel • Acro-Bond Plus
• PPG • Duracron
• Polycron III
• Valspar • Flurocryl
• Dynapon
AAMA 2604
South Florida Weathering
Color Retention 5 years – 5 Delta E
Chalk Retention 5 years – Chalk = 8
Gloss Retention 5 years – 30% retention
Erosion Resistance 5 years – 10% loss
Dry Film Thickness 1.2 mils minimum
Pretreatment System Chrome or Chrome Free
Accelerated Testing
Salt Spray 3,000 hours
Humidity 3,000 hours
AAMA 2604 Paint Specification
AAMA 2604 is an “intermediate” specification. A typical paint to meet this spec would be a 50% Fluoropolymer.
A typical application for this paint would be storefront, doors and other high traffic areas. This finish will provide you with good color and gloss retention. It will also provide good hardness and reasonable abrasion resistance.
AAMA 2604 - 50% Fluoropolymer Coatings • Attributes
• Good hardness
• Good color and gloss retention
• Achieves AAMA-2603 and AAMA-2604
• Moderate cost
• Limitations • Limited gloss range (25-35% reflectance)
• Applications • Cost-sensitive exterior applications (storefronts, doors,
high-traffic areas)
Kynar and Hylar are not finished paints, they are trade names for the PVDF resin used in high-performance Fluoropolymer paint coatings
50% Fluoropolymer Coatings Manufacturer Trade Names
• Akzo Nobel • Aluma-A-Star 50
• Aluma-Escent
• PPG • Acrynar FX
• Valspar • Acroflur
• Acrodize
AAMA 2605
South Florida Weathering
Color Retention 10 years – 5 Delta E
Chalk Retention 10 years – Chalk = 8
Gloss Retention 10 years – 50% retention
Erosion Resistance 10 years – 10% loss
Dry Film Thickness 1.2 mils minimum
Pretreatment System Chrome or Chrome Free
Accelerated Testing
Salt Spray 4,000 hours
Humidity 4,000 hours
AAMA 2605 Paint Specification
AAMA 2605 is the high-end exterior specification. A typical paint to meet this spec would be a 70% Fluoropolymer.
These finishes exhibit outstanding resistance to humidity, color change, chalk, gloss loss, and chemicals.
A typical application for this finish is large monumental architectural projects.
AAMA 2605 - 70% Fluoropolymer Coatings • Attributes
• Excellent color and gloss retention
• Excellent chemical resistance
• Achieves AAMA-2603, AAMA-2604 and AAMA-2605
• Limitations • Limited gloss range (25-35% reflectance)
• Fair hardness
• Higher cost
• Applications • Exterior products
• Recommended for monumental projects
Kynar and Hylar are not finished paints, they are trade names for the PVDF resin used in high-performance Fluoropolymer paint coatings
70% Fluoropolymer Coatings Manufacturer Trade Names
• Akzo Nobel • Trinar
• Trinar Ultra
• PPG • Duranar
• Sunstorm
• Duranar XL
• Sherwin Williams • Shernar
• Valspar • Fluropon
• Fluropon Classic
• Fluropon Classic II
• Flurospar
Fluoropolymer Paint Coatings • Kynar 500 & Hylar 5000 are types of fluoropolymer or PVDF resin used in a
70% PVDF resin based coatings that meets the AAMA 2605 specification
• Kynar 500 & Hylar 5000 have a long standing proven track record
• Kynar 500 & Hylar 5000 are the resin part of the paint coating
Resin System When people describe paint systems, they are typically referring to the resin system incorporated in the paint
Resin System
• 70% fluoropolymer paints – 70% of the resin component is
• 50% fluoropolymer paints – 50% of the resin component is
• Baked enamel – 100% of the resin component is acrylic or polyester
The resin system determines the properties and performance of the paint
Typical gallon of 70% PVDF liquid paint
10% pigment 20% resin 70% solvent
Weatherability • Chalking
• Fading
This is an actual warehouse painted in 1981 with different resin systems
What Causes Chalking Chalking is caused by a degradation of the resin systems at the surface of the finish, due predominantly to Ultra Violet (UV) rays. As the resin system breaks down, resin particles along with imbedded pigment particles lose adhesion and take on a white appearance.
Chalking is measured on a numerical scale. The higher the number, the better the chalking performance.
Failure in the Resin System Causes Chalking Examples of Chalking
Surface of the paint is breaking down (able to wipe off with your hand)
A tree brushing against this building has rubbed the paint off because it had chalked
What Causes Color Fade Fading is caused when substances in the environment attack the pigment portion of the paint and cause the color to change. Paints that have a high resistance to fading have a lower reading.
Failure in the Resin System Causes Color Fade
Failure in the Resin System Causes Color Fade
Warranty Information – AAMA 2605 Paint Type Chrome Pretreatment Non-Chrome Pretreatment
Valspar – Fluropon Up to a 20 year warranty including adhesion
Additional testing and chrome primer must be used to receive a 20 year warranty that includes adhesion
PPG – Duranar Up to a 20 year warranty including adhesion
No warranty on seacoast projects. Up to ten years on other projects
Akzo Nobel – Trinar Up to a 20 year warranty including adhesion
No adhesion warranty unless Akzo has tested and approved the pretreatment system
Fluoropolymer paint suppliers promote Chrome Phosphate pretreatment for the maximum corrosion protection available.
“Most field failures trace back to improper pretreatment,” says industry expert Manny Mayer. He puts the percentage at 90% or greater
Points to specify for a painted finish • Refer to AAMA-2605, AAMA-2604, or AAMA-2603
• Name 70% PVDF resin-based coatings for exteriors
• Specify minimum 40 mg/sq ft chrome pretreatment to ensure maximum long-term adhesion
Environmental Considerations • VOC’s –Specify all paint applicators must utilize a solvent
capture system and thermal oxidizer
• Chrome – Specify all paint applicators must use wastewater recovery system to minimize chrome waste, and applicator complies with all hazardous waste disposal regulations
Strengths of Paint • Vast choice of color
• Excellent exterior performance (70% PVDF)
• Field touch-up and repainting
• Small batch and custom colors fast and cost effective
• Seacoast performance
• Over 40 years of success in North America
• Available with antimicrobial protection infused in the coating
Limitations of Paint • Higher cost
• Inconsistent appearance of metallic paints
• Susceptible to scratching, especially the highest-performing 70% PVDF coatings
Powder Coating
What is Powder Coating • Same basic process as liquid painting
• With the exception of using dry powder rather than wet paint
• A mixture of finely ground particles of pigment and resin, which are sprayed on the surface to be coated
• The dry powder melts and blends in the cure oven
Powder Coating Line
Points to Specify • Uses the same AAMA specifications as liquid paint. AAMA-2605,
AAMA-2604 and AAMA-2603
• Specify minimum 40 mg/sq ft chrome pretreatment to ensure maximum long-term adhesion
Powder Coat Trade Names
AAMA 2603 AAMA 2604 AAMA 2605
Akzo Nobel Interpon D1000 Interpon D2000 Interpon D3000
IFS Coatings Ecuracote 03 Ecoset 04 Fluorset FP / Ecoset 05
PPG Envirocron Duranar
Sherwin Williams Powdera 3000 Powdera 4000 Powdera 5000
Spraylat Arc 2001 Decaflon
Tiger Drylac Series 29 / 17 Series 58 / 68 Series 75
TCI 10000 Series 11000 Series
Strengths of powder coating • Hardness and scratch resistance – particularly for commercial products like
lawn mowers, bike frames and appliances that utilize a AAMA 2603 product
• Environmentally Friendly – minor VOC emission
• Large job cost may be equal or slightly less than a 70% PVDF liquid coating
Limitations of Powder Coating • Small custom color jobs are more expensive and longer lead times
• Warranty - varies by supplier. • Many are more restrictive and limited as compared to 70% PVDF liquid coatings
• Metallic coatings – can only hold 30% of the metallic flake content as compared to AAMA 2605 liquid coatings
• Touch up – air-dry paint must be matched in a liquid paint for touch-up and field repairs
• Samples and color matches – no in-house blending of powder coatings • Lead times can be up to 4 weeks
Touch Up Paint • Does not have the same adhesion or durability as the factory applied
coatings
• Will exhibit chalking and fading characteristics noticeably faster
• Should be used as sparingly as possible
• Intended only to cover small blemishes or to touch up exposed cut ends on fabricated parts
Summary Comparison of All Finish Types
Weathering Performance
Finish Options Paint Systems Anodize Systems
Baked Enamel 50% PVDF 70% PVDF Class II Class I
Color & Gloss Poor1 Good2 Excellent3 N/A Excellent
Chalk Resistance Poor1 Good2 Excellent3 N/A Excellent
Color Options Extensive Extensive Extensive Few Few
Gloss Options 10-90 20-40 20-40 10-804 10-804
Hardness Very Good Good Fair Very Good Excellent
Salt Spray Resistance Poor Fair Good Very Good Fair
Chemical Resistance Fair Good Excellent Fair5 Good5
Effect of Poor Quality Substrate Moderate Moderate Moderate Significant Significant
Initial Cost Low Moderate High Very Low Low
Finish Performance Comparison
1 Meets AAMA-2603 2 Meets AAMA-2603 and AAMA-2604 3 Meets AAMA-2603, AAMA-2604 and AAMA-2605 4 Dependent solely on the individual substrate 5 Except for highly alkaline solutions – very poor performance
Include this guide specification for high-performance architectural coatings in your Master Spec
Restoration and On-Site Painting Samples for Specified Projects
Copper Anodize Finishes
Antimicrobial Protective Coatings
Additional offers by Linetec
www.linetec.com
Thank you for your time and attention Please continue to the next slide to take your test
Take test now