How do I clean a grimy street sign?
November 11, 2017 3:29 PM   Subscribe

My decommissioned NYC street sign is dingy and dirty, but I don't know how to clean it properly. What solvents or materials can I use to clean it without damaging it?

I've scrubbed with soap and water, with limited success. I've also tried a Magic Eraser.

The main problem is that there are streaks and blotches of black/gray material on the sign that seem likely organic. Is there a coating on these signs that will be damaged if I use something like acetone to try to remove them?

The street sign is one of these (but much dirtier than the ones in this photo).
posted by yellowcandy to Home & Garden (13 answers total) 2 users marked this as a favorite
Goof off is my go-to in these situations. The can specifically refers to removing "road grime".
posted by she's not there at 3:38 PM on November 11, 2017

Acetone seems a bit risky. You might try Simple Green before you escalate to anything harder. It's quite good at degreasing and breaking down stains.
posted by halation at 3:59 PM on November 11, 2017 [7 favorites]

Do you think it might be pine tar or tree sap? If so, olive oil on a cotton ball will usually remove it.
posted by pseudostrabismus at 6:14 PM on November 11, 2017

Try vinegar.
posted by vrakatar at 6:28 PM on November 11, 2017 [1 favorite]

Denatured alcohol?
posted by AnOrigamiLife at 7:41 PM on November 11, 2017

Goof off or orange oil will get rid of any greasy stuff. I would avoid acetone unless as a last resort.
posted by danapiper at 7:44 PM on November 11, 2017

Eucalyptus oil will take basically anything off.
posted by Jilder at 4:53 AM on November 12, 2017

Acetone will dissolve many types of paint, I definitely wouldn’t use it for a painted sign.
posted by insectosaurus at 9:22 AM on November 12, 2017

Whether it is painted or is a stencil over retroreflective film makes a big difference. If the latter, I suspect 3M has a datasheet that specifies exactly what solvents you must avoid.

If it's an old painted sign, don't use anything that will affect lead paints, since that's likely what was used. (Possibly with embedded glass beads depending on the age)
posted by wierdo at 6:22 PM on November 12, 2017

Should have looked at the pics. They are almost certainly a plastic sheet film given that era. Abrasives will likely make it dull if not wear through entirely. 3M datasheets will be your best bet for figuring out what kind of plastic it is and thus what solvents it will tolerate. Even if it is from some other manufacturer, the plastics will be of the same class.
posted by wierdo at 6:26 PM on November 12, 2017

Definitely try something like Goo Gone before resorting to acetone or products that contain acetone (like Goof Off).
posted by Quiscale at 8:59 AM on November 13, 2017

Just an update: I've tried orange oil, Goo Gone, and Simple Green. No luck so far.

Off to try Goof Off.
posted by yellowcandy at 9:23 PM on November 16, 2017

Window cleaners usually have ammonia, which is a great grease cutter. Get ammonia from the grocery store and mix it with a double amount of water and a pump spray bottle or you can use a sponge. Do it out on your balcony or garage - someplace with good ventilation.
posted by bonobothegreat at 8:16 PM on November 23, 2017

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