Surface Preparation and Overcoating of Factory-Applied Finishes James D. Machen KTA-Tator, Inc.

Surface Preparation and Overcoating of Factory-Applied Finishes – Overview of Presentation Objectives… 1.Where and why factory finishes are used 2.Generic types of factory finishes 3.How to assess the physical condition of a factory finish to determine overcoat viability

Webinar Learning Objectives (con’t) 4.How to prepare a factory finish for overcoating 5.How to identify candidate overcoat materials 6.Use of coatings test patch to validate surface preparation and overcoat options 3

Uses for Factory-Applied Finishes Standing Seam Roof Panels Building Facade Panels Canopies Awnings Curtain Walls Railings Window Frames/Mullions 4 Other Decorative Architectural Metal

Metal Substrates to which Factory Finishes are Applied Galvanized sheet metal –zinc or zinc/aluminum (trade names such as Gavalume ®, Zincalume ® ) Aluminum sheet metal Aluminum extrusions Sheet metal is typically supplied in “coils” that are coated in a “coil coating” process. Extrusions are typically coated by spray application. 5

Generic Types of Factory Finishes Fluoropolymers Polyesters Silicone modified polyesters Acrylics 50% to 70% fluoropolymer (PVDF) formulations are typically superior. Performance qualities of factory finishes are enhanced by post baking. 6

Common Factory-Applied Finishes ASTM A755/A755M – 11, Standard Specification for Steel Sheet, Metallic Coated by the Hot-Dip Process and Prepainted by the Coil-Coating Process for Exterior Exposed Building Products –Exposed side – polyester, silicone polyester, acrylic, fluoropolymer, plastisol, polyurethane –Interior (protected side) – polyester, acrylic 7

Common Factory-Applied Finishes (cont.) AAMA (Architectural Aluminum Metal Manufacturers Association) 2603, Voluntary Specification, Performance Requirements and Test Procedures for Pigmented Organic Coatings on Aluminum Extrusions and Panels –Least rigorous of the 3 AAMA standards –1 year South Florida Exposure –Good level of performance and general appearance – typically interior exposure –Baked polyester and acrylic 8

Common Factory-Applied Finishes (cont.) AAMA (Architectural Aluminum Metal Manufacturers Association) 2604, Voluntary Specification, Performance Requirements and Test Procedures for High Performance Organic Coatings on Aluminum Extrusions and Panels –Middle of the 3 AAMA standards –5 years South Florida Exposure –High level of performance and general appearance –Silicone-modified polyester and 50% polyvinylidene fluoride (PVDF) 9

Common Factory-Applied Finishes (cont.) AAMA (Architectural Aluminum Metal Manufacturers Association) 2605, Voluntary Specification, Performance Requirements and Test Procedures for Superior Performing Organic Coatings on Aluminum Extrusions and Panels –Most rigorous of the 3 AAMA standards –10 years South Florida Exposure –Superior level of performance and general appearance –70% polyvinylidene fluoride (PVDF) 10

Benefits of Factory-Applied Finishes Factory Finishes Provide Excellent…….. Weathering characteristics Color and gloss retention Corrosion protection Automotive-like finish Long term performance 11

Manufacture Warranties 10 and 20 year warranties depending on local exposure conditions: –Intensity of UV exposure –Airborne pollutants –Chloride, seacoast exposure –Time of wetness –Installation Orientation (vertical vs. low angle) 12

Warranties Cover Peeling Gloss reduction greater than X Color shift greater than Y NOTE: Warranties for exterior exposure do not claim that color and gloss will not shift, but that the shift will be less than a certain amount compared to original baseline measurements. 13

Maintenance of Factory Finishes Maintain as long as possible by…… Periodic detergent washing and cleaning Cleaning every 6 months prevents build up of chloride and acid salts Cleaning removes debris that increases time of wetness Clean mildew and fungal growth at same time (1 gallon household bleach, cup of soap, 5 gallons water)

Use Repainting as Last Resort Painting introduces risk of peeling….. –New coating to factory finish –Between factory finish and substrate Field-applied coating will not have the same automotive look 15 Systematic steps for assessing the condition, preparing the surface and overcoating factory finishes are required.

Systematic Approach of Assessing Factory Finishes for Overcoating Steps Consist of……. STEP 1 – Determining the Generic Type of Existing Finish STEP 2 – Assessing the Condition of the Factory Finish STEP 3 – Preparing the Factory Finish for Overcoating STEP 4 – Choosing Candidate Overcoat Materials STEP 5 – Performing a Coatings Test Patch 16

STEP 1 – Determine the Generic Coating Type of Existing Finish Make Determinations By……. Reviewing original specification or project procurement documents –Be aware of alternate or substitute products Manufacturer’s warranty documents may identify material suppliers or manufacturers, product trade names or the shop applicator –Shops oftentimes use sole source of supply 17

STEP 1 – Determine the Generic Coating Type of Existing Finish (cont.) If all else fails… Laboratory Analysis to identify generic type 18  Infrared Spectroscopy

STEP 2 – Assess the Condition of the Factory Finish Involves a series of sub-steps to determine the suitability of the existing factory finish for overcoating. 19 Visual Assessment  Lifting, Peeling  Rusting (use SSPC-VIS 2 pictorial standard to characterize and quantify rust)

20 STEP 2 – Assess the Condition of the Factory Finish (cont.) Paint Thickness  Determine representative thickness range

–ASTM D – Measuring Adhesion by Tape Test –ASTM D 6677 – Standard Test Method for evaluating Adhesion by Knife Test –ASTM D 4541 – Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers 21 STEP 2 – Assess the Condition of the Factory Finish (cont.) Adhesion – A “sound foundation” for overcoating

Knowing the Physical Characteristics of the Existing Coating Helps to determine Associated Risk Level Guidance typically provided by the overcoat material manufacturer Other industry publications and documents –SSPC-TU 3, Overcoating 22 STEP 2 – Assess the Condition of the Factory Finish (cont.)

STEP 3 – Prepare the Factory Finish for Overcoating Hand and/or Power Tool Cleaning –SSPC-SP 2 or SP 3 to remove loose deteriorated coating or metal oxidation (corrosion) –Feather-edge transition (dull putty knife test) 23 Used to review candidate methods of surface preparation

Pay attention to…..  Field cut edges  Field formed surfaces (tooling damage)  High foot traffic areas  Ice damage areas 24 STEP 3 – Prepare the Factory Finish for Overcoating (cont.)

Overall Surface Cleaning –Remove dirt/grime/oil/other contaminants by pressurized water cleaning –Fan angle of pressurized water – 0 , 15 , 25  –Be careful not to damage intact coating or substrate with pressurized water 25 STEP 3 – Prepare the Factory Finish for Overcoating (cont.)

Brush-off Blast Clean –Control process – lower air pressures, use fine/soft abrasives, increase stand-off distances 26 STEP 3 – Prepare the Factory Finish for Overcoating (cont.) Surface Roughening  Superficial roughening only, no coating or substrate damage  Dull gloss/sheen Sanding  Use fine grade of sandpaper

Use Less Aggressive Abrasive Media or Methods –Urethane foam sponge, walnut shells, crushed glass, fine garnet, other hybrid mixtures –New low impact technologies utilizing water vapor and low operating pressures 27 STEP 3 – Prepare the Factory Finish for Overcoating (cont.)

Goal of Surface Roughening ….. –Provide a uniform and dense surface roughness in a continuous pattern of peaks and valleys with no smooth, un-profiled areas. –Not damage the intact coatings or the underlying substrate 28 STEP 3 – Prepare the Factory Finish for Overcoating (cont.)

STEP 4 – Choose Candidate Overcoat Materials Candidate Overcoat Materials Qualities….. Compatible with existing factory finish Field application friendly Good adhesion characteristics Suitable for the intended exposure environment Capable of producing the desired finish appearance 29

Compatibility with Existing Factory Finish is best determined by…… –Proven history of performance Air drying fluoropolymers (FEVE) Advanced acrylic formulations or…… 30 STEP 4 – Choose Candidate Overcoat Materials (cont.)

STEP 5 – Candidate Coating Test Patches Confirms and validates information obtained from previous steps. May include evaluation of multiple surface preparation and coating types ASTM D5064, Standard Practice for Conducting a Patch Test to Access Coating Compatibility Test Patch Exposure Time –Minimum – after full manufacturer curing intervals –Optimal – 6 mos. to 1 year – cyclic weathering –Generally, the longer the exposure time, the more useful the information for predicting risk 31

In conclusion, key steps include… 1.Determining the type of the existing finish 2.Assessing the physical characteristics of the existing finish 3.Reviewing candidate surface preparation methods 4.Reviewing candidate overcoating materials 5.Incorporating information obtained in Steps 1 through 4 into a Coatings Test Patch Program 32 Conclusion

Make an Informed Decision The above steps provide valuable information for an informed decision. Process requires… Initial expenditure of –Time –Money –Manpower Minimizes “guess” work of overcoating 33

34 Surface Preparation and Overcoating of Factory Applied Finishes Questions?