I received a call this afternoon about an all metal sign we installed about a month ago. The sign has metal faces with plastic changeable letter tracks attached across the lower half. The gentleman said his sign was starting to rust and asked that I come and see for myself. I went by after work and sure enough, the sign has little rust specks all over one side with the rust being quite pronounced underneath the plastic tracks. Now here's the "kicker": the sign is all aluminum. Anyone have a clue about what this could be! I have to tell the guy something.
Posted by Mike Pipes (Member # 1573) on :
Aluminum oxidizes when it's left bare and outdoors.
You can clean it off with one of the many "metal brighteners" out there, as well as something like Meguiar's All Metal Polish or Mother's Mag & Aluminum Polish.
Of course it's just gonna do it again so if you want to prevent it from happening you need to treat the aluminum somehow, like painting it or clearcoating it.
Posted by James Donahue (Member # 3624) on :
Red-brown rust, as in FERROUS OXIDE rust? If I'm not mistaken, when aluminun oxidizes, it's a white-ish kind of color. This IS strange.
Maybe it's close to the road, and this is road grime. Maybe steel rivets to put the tracks on. If it's coming through the paint, I'm clueless. I would put a magnet up to it to be sure it was aluminum I used.
Posted by Roy Frisby (Member # 736) on :
Additional info: The aluminum is prefinished with baked on white enamel and all rivets are aluminum. The rust is not aluminum oxidation, it is rust red as in iron oxide. I'm leaning toward the stuff being some type of industrial pollution but a somewhat older sign across the street shows no evidence of it.
[ November 10, 2003, 09:43 PM: Message edited by: Roy Frisby ]
Posted by Dennis Raap (Member # 3632) on :
I had this type of thing show up on a light colored pickup, we figured out that one of the guys in the shop had used a hand grinder in that area a couple of days before. The metal that had embedded it self in the paint didn't show up until it turned to iron oxide a couple of days later. Posted by Mike Duncan (Member # 316) on :
Roy, Sounds like maybe some fine iron or steel from grinding. I've had signs sit in the shop, then when brought outside and rained on, the grinding dust rusts. Was anyone grinding around it maybe? Mike
Posted by Curtis hammond (Member # 2170) on :
Gringing around it, .or welding or torching around it..
Or hard water rust stains from a water lawn sprinkler..
[ November 11, 2003, 12:29 AM: Message edited by: Curtis hammond ]
Posted by Gavin Chachere (Member # 1443) on :
Roy is it near some kind of watering system? even from rain water aluminum won't rust but the mineral content of the water will settle out and rust on the surface..happens alot after people use aluma prep and metal prep to kill rust.
Posted by Harris Kohen (Member # 2139) on :
Roy,
My vote is with Dennis, Mike, and Curtis on this one, either grindings got into the surface or someone was welding in close proximity to the aluminum panels. thats about the only way aluminum will rust the way you explain. rust is oxidation, aluminum oxidizes, but its not going to be red or even reddish.
I bet if you contact your local aluminum supply house, not sign supply, ask them about it, they can probably explain it to you.
GOOD LUCK
[ November 11, 2003, 01:05 AM: Message edited by: Harris Kohen ]
Posted by Ian Stewart-Koster (Member # 3500) on :
Sounds very much like iron filings embedded in the face. Should polish off.
Posted by old paint (Member # 549) on :
roy is there a steel mill, steel manfactureing,trailer builder, some huge steel workin facility near there? i worked at a steel mill, bought a brand new car....put it in the mill parking lot....and had same thing.
[ November 11, 2003, 02:57 AM: Message edited by: old paint ]
Posted by Ray Rheaume (Member # 3794) on :
Roy,
What kind of screws did you use to attach the tracks? Maybe they are rusting and the rust is just creeping along the tracks.
Rapid
Posted by BrianTheBrush (Member # 1298) on :
Here's something else to consider..whether this is causing any problems YET, is doubtful, but just something to think about.
Unlike metals, in contact with each other, can cause premature corrosion and oxidation. I've seen race car trailers that weren't two years old start to "rust" for all intents and purposes, where the aluminum skins meet the steel braces and frames. If this aluminum sign has a steel structure supporting it, placing some dielectric buffer material between the two unlike metals will prevent, or at least slow down this process.
Posted by Roy Frisby (Member # 736) on :
We gave it a good going over today with soap and water. Most of the rust came off. So we'll see if that did the trick. Thanks for the replies everyone.
Posted by Monte Jumper (Member # 1106) on :
Sounds like mildew to me or maybe a red fungus.
Is this in a really shady area where there is a lot of humidity?
Posted by James Donahue (Member # 3624) on :
Mystery solved???
The sign is aluminum, with aluminum rivets, BUT, the rivets MANDRELS are steel, eh? If I'm not mistaken, part of the mandrel breaks off and stays in there. Maybe not, but this would explain why the rust is worse where the tracks are.
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