Thread: Rust removal with molasses.

Originally Posted by VladTepes

The follow up Q of course is... one one removes all the rust from old tools (as I'm planning) how then do you prevent the tools from rusting again?

Use usually works.

But if like most where we don't use our tools daily you then need to prevent oxygen and moisture from getting to the surface of the metal. Garden tools get a coat of linseed oil on the wooden handles and the metal surfaces, other substances such as lanolin have been used on a broad range of hand tools from cabinet makers tools to rotary machine cutting tool metal surfaces. Short of barriers such as the easily removed oils then you get the hard setting barriers like paints and then the sacrificial coatings or platings some of which are barriers. Take your pick.

Wipe the newly de-rusted tools with a cloth moistened with Lanotec and then let the tool dry. Once it's dry the Lanotec coating will survive (almost) being sprayed with a 70 Bar power washer....

Bit of grave digging, but this may save you all a lot of time and money.

Have tried molasses, yes it works, takes time.

In the process of de rusting a 4000 gal tankstand in pieces. Have two capped 100mm sewer tubes 4m long sitting diagonally to the ground, one full of fermented molasses, one full of 20% phosphoric acid.

After 4 days in the molasses tube there is a bit of action........ some rust has gone (maybe 10%).

After one day in the phosphoric tube all rust is gone, including pits and paint.

I know from experience to just let the phosphoric treated steel dry and keep it dry till primed.

Don't rinse the finish off!

Maybe just wipe with a dry rag before priming (I have my own special for that).

20 L of 83% phosphoric cost me $65 a couple of years ago through an ag trade account. Pretty cheap when diluted to 20%. Most commercial similars are 17% at most.

To de-rust this whole thing is going to cost me $30 max for acid.

cheers, DL

It's probably better practice to carefully wash off any excess phosphoric acid with water. When the phosphoric acid has done its work, there should be a deep grey/black finish on the iron. This is iron phosphate, it is chemically bonded to the substrate and is quite insoluble in water. Gently washing off remaining acid with water and allowing the surface to air dry will then get rid of any excess phosphoric acid and provide a better etching surface for the primer to adhere to... and not interfere with subsequent coatings.