Remove rust using molassas

[dickb]

I heard about removing rust using molassas, what nonsense. 

But I had half a bottle in the refrigeraor and decided to give it a try. 

I put an old hammerhead covered mostly with rust and some remnants of the original red paint into a half and half mixture of molassas and water and sealed it up in a glass jar and put it out on the porch. Nothing happened for a couple of days. 

I left it soak for the rest of the week. 

Then I noticed some yellow scum floating on top and checked it again. The rust had turned to a black sludge that you could rub off with your fingers and the paint had loosened up to the point that it could be removed with a nylon scrub brush. 

I have used vinegar to remove scale but the stink is too much for me.. Does anyone understand whats happening with the molassas ??  

[Frosty]

Yes. It's the phosphorus content in molasses that removes rust, it's just not concentrated enough to do it quickly. It doesn't actually "Remove" rust it scavenges the oxygen from it reducing the rust back to iron or steel

Next time try club soda or better yet dilute Naval Jelly 1:1 with water and soak, that will "derust" a BAD case over night but will acid etch if you leave it too long. Naval Jelly is phosphoric acid, a surfacant and a thickener. The thickener is there so you can brush it onto horizontal or overhead surfaces and have it stick.

When you remove the piece from any of these derusting baths rinse, neutralize with baking soda in water and rinse again immediately. Pospohric acid oxidizes quickly and leaves a flat black patina on steel. That's what the black scum in your molasses bath was, oxidized phosphoric acid. It was telling you it needed more molasses.

Frosty The Lucky.

P.S. It's not nonsense you just have to know how like anything. 

[Irondragon Forge ClayWorks]

The best molasses (unsulphered) to use is from the feed store (not grocery store). I have used it on old antique muzzleloaders a mixture of 7 parts water to 1 molasses.