I have read many Instructables suggesting many ways to de-rust items.
I have even tried a few with variable results, so I decided that it was time to do a definitive test.
This is that test.
Step 1: The Apparatus
This could be done using any containers but I decided to make a neat set up using cut off and inverted Coke bottles.
I had an IKEA plastic shelf that I flipped on it's side, then drilled 5 holes in it, using a step bit.
Next I cut off 5 bottles and 'screwed' them into the holes.
The caps were screwed back on tight, and everything tested for leaks with water, before pouring in the test liquids.
Step 2: The Methods to Be Tested
I set up; One Lemon juice, One White wine Vinegar, One Cider Vinegar, One regular Vinegar and a Soda Crystal based electrolysis one.
Step 3: The Test Subjects
I had previously left a bunch of iron screws out in all weathers to get rusty.
There was approximately 6 months rust on them.
I selected ones that seemed to have the same degree of rust to aid comparison of results.
Step 4: The Method
The containers were filled with enough of each liquid to cover them. The electroysis one had a half tablespoon of Soda Crystals mixed with water and connected to a 12v battery charger. (+ve to the sacrificial anode and -ve to the rusty screw.)
Step 5: Bonus Test
Since I often read that Coca Cola can clear rust, I decided to also test that liquid in a separate cut-off bottle.
Step 6: The Results
After an overnight soak, each was removed and cleaned with a wire brush.
No electric tools were used, just a little brush up, to treat each one equally.
Step 7: How They Stacked Up
You can zoom into the image to inspect each screw and judge for yourself the different results.
Personally I see very little difference.
The good news is that each of these methods DOES clean off rust and does get an item back to a usable condition.
There is 'maybe' just maybe, a slightly better result from the Cider Vinegar but it really is too close to call.
Coke is not really a viable option, since it costs more and does a bit less.
The electrolysis method is fiddly and shows no real benefit on this sample. Maybe it is more suited to larger items that can be immersed in large tubs, since it would be prohibitively expensive to fill a large tub with any of the vinegars.
However, by using suitable plastic bags it is possible to envelop even a large object and lay it down so that it needs less vinegar to cover it.
Step 8: Another Specific Test
To test the bag method I placed a rusty key in a zip bag with a little vinegar.
Step 9: The Key Result
After just a few hours and a light brush up, the difference was remarkable.
I then coated it with Olive Oil which should help stop it going rusty again.
It is quite important to oil the results of rust treatment quickly, since I have noticed that they seem to rust faster if you do not coat them.
I used Olive oil but many others should be fine. (Maybe someone would like to do a test of oils?)
Step 10: Messy Containers or Plastic Bags
Having tried de-rusting in several different plastic containers I am now of the opinion that it is far better to use zip bags or even large storage bags to minimize the amount of liquid needed to coat the item.
The results are good and the clear up is better.
Step 11: Summary
So this is what I think:
- The results are simply; that all methods do clear up the surface rust.
- The cheapest effective substance is ordinary cheap vinegar.
- All methods still require abrasion to clean off the loose matter.
- All methods still need further polishing or even grinding to get to bare metal.
- The use of zip bags or poly bags can reduce the amount of vinegar needed to coat the item.
- It is far better to not allow items to get rusty in the first place.
- Rust can easily be prevented by storing in a dry place, using a desiccant and coating in a light oil.
- The best effective coating is basic olive oil (no need for extra virgin).
- Look after your items and avoid having to use any methods to de-rust.
This was a very interesting exercise for me.
I felt like I was a student in America doing a science project. (Hey kids, this may be an idea for your next one).
Step 12: Rust in Peace
Having said that it is best not to let things get rusty, the fact is however, that we all do.
I do have a few items that require my attention.
It looks like I will be buying vinegar by the gallon....
Step 13: Addendum Feeling Pasty
I have since tried many ways to contain the liquid whilst it works it's magic on the rust.
One such method is to make a paste.
I looked around the web but did not see what I was looking for and so I tried this method.
Step 14: Mix It Up
I poured Cider Vinegar into a cleaned out plastic butter tub.
Next I poured in Soda Crystals.
I kept adding and mixing until I had thick paste.
Step 15: Spread the Goo
Once I was happy with the consistency, I then spread it over a rusty hand saw.
I then left it over night...
Step 16: The Next Day
I scraped off the crud and brushed the metal with a wire brush.
The result was a blackened but clear area.
I then tried just Vinegar over the end section and the result is as you can see in the last picture.
One conclusion is that a paste does clear rust, but is best not left on for more than a few hours.
Another conclusion is that treating metal after the first dunk and brush can help to get back to good metal.
My last conclusions are that the paste saves liquid and is good for large surfaces or vertical surfaces such as on metal legs or a panel that cannot be treated any other way.
It is definitely something to have in your rust beating armoury.
Step 17: What Next?
I have had some encouraging feedback from this little experiment and so I have decided to undertake two more.
The first will be using proprietary products such as Evaporust or Kurust.
Please do leave a message mentioning the names of any products that you would like me to include.
The second 'experiment' will be into the best ways to prevent rust using either proprietary methods or home made ones.
The preservation challenge has already started and will run for around 3 months to allow for results to be known.
Please do follow me if you would like to know when the new 'ibles are published.
Thanks for your interest.