Here is the directions off my box of OA:
Directions: Rust Stain Remover
Wet the stain and sprinkle PURE OXALIC ACID on it. Rub with a wet cloth, sponge or brush until stain has vanished. Rinse thoroughly and wipe dry. For more stubborn stains, make a paste of PURE OXALIC ACID and water, apply to the stain and allow to stand a minute or two before rubbing. Rinse and wipe dry. To whiten iron stained clothes, presoak using 4 tablespoons of PURE OXALIC ACID in 2 gallons of water. PURE OXALIC ACID can also be sprinkled in the toilet bowl and other porcelain surfaces to clean embedded rust and hard water stains.
Source:
http://www.empireblended.com/enginee...xalicacid.html


Like I said above, a paste made with Zud cleanser and OA, rubbed or steel wooled onto the surface works in a few minutes.

Borax will neutralize the OA, if needed.

I thought the fork on the Rossin was junk, but as you can see in my earlier post, a bit of elbow grease and OA works wonders.