My 11 year old nephew came to visit me over Christmas. Let me just say, nothing is more fun for a tinkerer than to spend time with a young curious mind. Before he even got his clothes up to his room we went to the workbench where I presented him with a hammer, pliers, and a couple of screwdrivers for his exclusive use.
We talked about tool safety and the rules of the house. Being 11 he sat quietly while I told him about keeping gates shut so the animals would not escape. He also learned that if he wanted to use a power tool to come get me. I did not mind him using the tools, I only wanted make sure he did not loose any fingers. As soon as I was done talking he quickly informed me that I had rusty tools and that he uses coke as a rust remover. (Did I mention that my wife kept telling me I had a mini-me all week).
Being the man I am, I had to explore this new idea. I asked him if he ever tried it (he hadn’t as his mother doesn’t let him “waste” food), I asked him if her knew why it worked, and I asked him if he wanted to see if it would work.
What Acids Take off Rust
We began our research and figured the phosphoric acid in the soda ate the rust off, and to try it we devised a little experiment.
William and I rusted some nails and then sat out a cup of mountain dew, coke, apple cider vinegar, and some water as a control. Out hypothesis was the coke would do the best.
The next day we were surprised that the coke was one of the worse at taking off coke. Mountain dew does a lot better, but vinegar does the best job of the liquids tested.
Upon further investigation we discovered that acids do take off rust. We also decided that of the items tested the vinegar was the most acidic.
As a side benefit the vinegar leaves a thin protective coating on the metal to help prevent further oxidation.
A warning is needed though – do this with something attached to aluminum and the vinegar may dissolve the aluminum… I learned this the hard way when I stored some homemade vinegar in milk jugs on a shelf above a rifle. The vinager eventually leaked and it pitted my rifle severely.