Best way to paint rusted metal

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Old 11-15-15, 07:05 AM
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Best way to paint rusted metal

Should I use one of those products that dissolve/"convert" rust or should I wirebrush/sand etc. before painting? Does primer actually do anything? Oil base top coat? This is on lawn furniture with grids, hard to sand.
 
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Old 11-15-15, 07:45 AM
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I've been using Rustex lately, and just washing rusty surfaces with soap and water and wire-brushing to remove the loose rust first. Rustex chemically converts ferrous oxide to ferrous phosphate . . . . which is inert and becomes your "primer". If you were to remove "all" of the rust, you wouldn't have any loose molecules of ferrous oxide available to create the iron phosphate. It only works on the exposed surfaces. If the surface gets scratched and exposed to oxygen, the ferrous oxide (rust) will begin to develop again.

When I just want to "remove" all rust, and not paint a surface, (like chrome bumpers, or porcelain bath room fixtures), I slowly wash them with Oxalic Acid (a POISON), which is often available by request, from your Pharmacist.
 
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Old 11-15-15, 07:48 AM
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I've been using Rustex lately, and just washing rusty surfaces with soap and water and wire-brushing to remove the loose rust first. Rustex chemically converts ferrous oxide to ferrous phosphate
Is naval jelly the same thing?
 
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Old 11-15-15, 09:17 AM
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Originally Posted by Norm201
". . . Is naval jelly the same thing? . . ."
I don't think so. There's more than one formulation of Naval Jelly, and most of them dissolve rust (similar to the Oxalic Acid) rather than convert it; so they have to be immediately coated again to protect them from being re-oxidized.

The Rustex I mentioned is a brand name from Supreme Chemicals of Georgia (aka Krud Kutter); but there are many others; some people claim that the Phosphoric Acid in Coca Cola does something similar . . . . but I've never tried that !

In my examples regarding Oxalic Acid, the Chrome Bumpers, they need a frequent application of chrome polish to seal the capilaries on the surface while the Porcelain is usually stained with ferrous oxide carried in the water that they process.
 
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Old 11-15-15, 10:16 AM
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Whether or not I used a rust converter, I'd still sand or wire brush the best I could and use a solvent base rust inhibitive primer.
 
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