Restoration Tips for Rusty Outside Thermometer Exposed to Elements for 50+ Years?

January 16, 2005 3:56 PM

I have a painted metal thermometer that used to hang on my grandparents' porch. It's very old (fifty years?), and very rusty, but I love it. It's so rusty that the advertising ("Whiskey Hill Grocery") and the temperature gradations are barely discernible. How can I remove this oxydation without damaging the paint underneath, restore the piece to something approximating its original condition? Is this even possible?
posted by jdroth to home & garden (3 comments total)

Is it actually painted? If so, it seems unlikely the rust is under the paint...

I think the only way to find out, is to try some rust removal products and hope for the best. Or live with it.
posted by phrontist at 4:03 PM on January 16, 2005

I don't believe that there is still an appreciable amount of paint underneath, as the paint would protect the metal from oxidation. Your best bet is to sand and re-paint. (Or just skip the sanding part and use a rust-proofing base coat, available in spray-paint form from your favorite spray-paint outlet)
Sanding (or sandblasting, if you have access to such tools) will give you the best re-finish though.
posted by defcom1 at 5:32 PM on January 16, 2005

As mentioned by defcom, the rust is the metal oxidizing, not a surface defect, for the most part. You could go over it very lightly with very fine (0000) steel wool, but in my experience this will only knock of fairly loose rust. If you take it down to bare metal with any abrasive, you'll most likely take off the paint, especially small marks such as temperature gradations. I've never had success retaining painted decoration when using abrasives.

There's an electrical method for rust removal which is a bit more involved, potentially dangerous, but also pretty unique in it's completeness and delicacy. This guy had good results.

This company is all about rust removal, and has a liquid solution they say is paint safe. I was aware of electrolytic methods, but never heard of a chemical solution which didn't melt paint as well.
posted by Jack Karaoke at 9:06 PM on January 16, 2005