Removing rust – the experiments (i)

In order to determine which of the chemical means of reducing corrosion works best, I set up a series of experiments.  The first one applied four different rust removers against the task of removing rust from a series of large and small vintage rectangular forged nails. The rust on these nails is fairly uniform, as opposed to plane blades, which can often form varying levels of rust, depending on the environment they are stored in, and their composition. Each nail is be submerged about one-third in a rust suppressing liquid – Evaporust, vinegar, molasses, and Coca Cola. The nails were left in the solutions in glass jars for 5 days.

Experiment 1: SMALL NAILS

The first experiment was done with small nails, approximately 2″ in length. Here are the nails before treatment:

And here are the nails after treatment with each of the four solutions. The result?

  • Molasses – The rust on the nail has been reduced substantially.
  • Coca Cola – There is no effect on the rust, in fact submersion in the Coca Cola has added a surface layer of flash rust.
  • Vinegar – Somewhat less effective than the molasses, the rust has been reduced, with a noticeable differential layer where the vinegar ends.
  • Evapo-rust – Cleanly and efficiently removed all traces of rust from the nail.

Experiment 2: LArge nails

The second experiment was performed with 4″ nails, in rougher condition. There were noticeably similar results. The side effect of these treatments is that as in the closed jar environment, vapours often have an effect on the portion of the nails not in solution.

  • Molasses – The rust on the nail has been reduced substantially.
  • Coca Cola – Again there is no effect on the rust.
  • Vinegar – Somewhat less effective than the molasses, the rust has been reduced, with a noticeable differential layer where the vinegar ends.
  • Evapo-rust – Cleanly and efficiently removed most traces of rust from the nail.

So from these experiments it is clear that using Coca Cola is not at all useful in the process of suppressing rust. It doesn’t work. Most colas have a pH of around 3.4, and is more acidic than vinegar, and citric acid. But it is essentially a  carbonated syrup.  Over a long period it may be effective in removing tarnish from some metals, but not in-grained rust. Apparently some people have had success using cola and aluminum foil to remove rust spots from chrome. Vinegar and molasses are somewhat effective given time, and more importantly they are cost effective, which is especially good for de-rusting large pieces.

 

 

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One thought on “Removing rust – the experiments (i)

  1. roccaways says:

    This is a timely post. Coincidentally I purchased a gallon of a competitor to Evapo-rust last night from Parts Source (non-acidic/non-corrosive/non-toxic etc, removes 1/2 pound of rust/gal. etc. which I interpret as a chelation solution like Evapo-rust). My internet “research” suggests that molasses naturally contains some of the chelating compounds found in the likes of Evapo-rust. I’ve had good luck with vinegar restoring handsaw plates and some success with hand planes. Hand planes are a little trickier to scrub out in the corners and since the vinegar actually consumes the good metal too, I hate leaving them too long. Vinegar also brings out a dull grey/black surface in metal, which generally isn’t a problem but a highly polished surface would be more impressive. My plan is to start heavily rusted components (and as you suggest, larger components) with vinegar and finish them in the chelating solution, and just put light rusted items directly in the chelating solution.

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