Aluminum Window Extrusions Paint Extent

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Author Message Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 540 Registered: 05-2003 Posted on Monday, April 07, 2008 - 05:25 pm:    Dumb question (could be due to lack of sleep) is the concealed side of the aluminum extrusion considered exposed? When the aluminum is painted in the factory are all sides painted the same number of coats? - a client asked if there was a way to reduce cost of a Kynar finish on aluminum window frames by stipulating that the concealed side is not painted - so is it or is it not? if the spec says to paint all exposed surfaces of the aluminum, what does this mean? My brain is not functioning right now, so do any of my colleagues have an intelligent answer for this one? Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 265 Registered: 10-2003 Posted on Monday, April 07, 2008 - 05:37 pm:    Jerome, Unless the extrusions are in 2 pieces (i.e. thermally broken), the aluminum receives the same finish, inside & out for storefront and aluminum windows. For Curtain Wall (pressure bar) the exterior cap could be a different color from the rest of the extrusion. What do you mean by "concealed side"? Do you mean the interior? If so, then it is "exposed to view" and must be painted. Hope this helps. Christopher E. Grimm, CSI, CCS, LEED®-AP, MAI, RLA Senior Member Username: tsugaguy Post Number: 139 Registered: 06-2005 Posted on Monday, April 07, 2008 - 06:55 pm:    This would only save money if it is a standard option, otherwise asking them to retool their product line to save on paint would be counterproductive, even though it is expensive paint. If you really need to know, call the rep. If it is design/build or negotiated, ask the contractor who they plan to use for the aluminum frames. If public bid, choose your least favorite rep and call them, that is who you probably would get. Another option for your owner to consider is to go with anodized. It is essentially the rust of aluminum, only in more attractive colors than the rust we all think of on steel, so it can't really wear out. If the limited color choice isn't a problem, you really can't go wrong (clear or satin, gray, black, sometimes champagne, and I think white too now). The main reason to spec Kynar is if you must have a wide range of colors. The 20 year warranty is nice, but the product still might not be scratch resistant. Powder coating is not widely mentioned in guide specs but it has a lot of possibilities including fluoropolymers like Kynar being applied electrostatically, among a host of other resins. If by concealed side you mean the part that meets the frames, that is actually even considered an optional separate piece by some manufacturers. We recently learned of the problems this can create, with nothing to compress and contain joint sealant backings, so we now add to the framing systems "Back Plates: Furnish jamb and head framing members with manufacturer’s standard continuous back plates." These members would not need any particular finish as far as I am aware. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 541 Registered: 05-2003 Posted on Tuesday, April 08, 2008 - 02:22 am:    In South Florida on the ocean, Kynar or Duranar for aluminum is far superior than Class I Anodized. Currently PPG is offering up to 25 yrs warranty on their finishes here. A popular color is Duranar Sunstorm Arcadia Silver. Powder coats don't seem to hold up. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 542 Registered: 05-2003 Posted on Tuesday, April 08, 2008 - 02:25 am:    Chris - when the frame fits into the opening and abuts the masonry opening, we prefer all surfaces to be painted to protect the aluminum from dissimilar surface reaction - but it is true that a 3 coat Kynar or Duranar finish is expensive, I don't like the risk though. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 873 Registered: 03-2002 Posted on Tuesday, April 08, 2008 - 09:13 am:    I have been advised by some architectural aluminum fenestration products manufacturers that Kynar is actually less expensive than Class I anodizing. Does anyone have any data on that? William C. Pegues, FCSI, CCS Senior Member Username: wpegues Post Number: 716 Registered: 10-2002 Posted on Tuesday, April 08, 2008 - 10:28 am:    Jerome, Richard, the first response, gave you the answer you need. The extrusions are coated on a coating line. Unless its a low end window you don't want to use, its an automated line. You can choose not to coat some extrusions, or to coat them, you can't choose to coat part of an extrusion. Even then, many window manufacturers run their own coating lines and even with an interior and exterior extrusion, they don't run 2 lines for a cheaper paint inside. Some do, some don't. But the difference would be the interior side extrusion vs the exterior side being different color. You can't chose to not coat the part of an extrusion that is 'concealed' in the wall. Coating types - powder coatings have no standard or standard system. That is, nothing governs their quality, and, you can powderize just about anything. You can powderize acrylics, enamels, alkyds, urethanes, polyurethanes - you can even powderize kynar based systems (though currently it is not common). What you get for lasting quality of the coating is totally dependent on the powderized material. Most window manufacturer's offering powder coatings, and most railing companies as well, use polyurethanes. Chalking, fading, and other aging of a powder coated material is somewhat better than a shop spray or coil coated version of the same material. Thus, most powder coated polyurethanes will have a standard warranty of 5 years, and you can often talk them into 10. Most powder coated systems cannot do metallic colors. The PPG color you references used the term 'Sunstorm' in the color. That is their series name for a "2-coat" mica based 'metallic' color. That is, its not a true metallic 3 coat system that uses aluminum flake for the metallic look. It uses mica as the flake. Since the mica does not need the protection of a clear coat like the aluminum flake does, its referred to as a 2-coat system. Less expensive than a true metallic 3-coat system. But, you can tell the difference, the Sunstorm coatings are not as sparkly looking as the same color in a true 3-coat metallic version. Both 2 and 3 coat 'metallic' coatings can be had in a 20+ year warranty from PPG William Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 266 Registered: 10-2003 Posted on Tuesday, April 08, 2008 - 10:48 am:    I have been told by a naval architect friend of mine that anodizing is probably the worst thing you could due for a project located near the ocean. It tends to pit and chalk overtime. I've seen this myself on sailboat masts. Bob Woodburn, RA CSI CCS CCCA LEED AP Senior Member Username: bwoodburn Post Number: 237 Registered: 01-2005 Posted on Tuesday, April 08, 2008 - 11:06 am:    I've seen unpainted aluminum pivots, presumably anodized, on cruise ship exterior doors that were eaten up with corrosion (not just pitted - they had huge, deep gaps, holes, missing portions -- beyond patching or repair). Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 749 Registered: 07-2002 Posted on Tuesday, April 08, 2008 - 03:21 pm:    John- about a year ago, we were getting anodizing at 10-15% MORE than Kynar, which completely surprised me, since my brain still thinks its 25 years ago when Kynar was 30% more expensive than anything else. apparently the clear anodizing isn't used that much anymore and the cost of the electricity used for the process has increased enough that the two together mean cost increase.