With one natural ingredient, it’s easy to remove rust from tools, heavily corroded antiques, and other metal objects.
Read on to learn how to remove rust with this simple method: Soak the rusty tool in citric acid for several hours, remove it from the water and wipe down the tool to remove rust from crevices. No elbow grease needed!
In this article, I show how this method removes rust faster than vinegar, easier than scrubbing, and naturally – without the harsh chemicals in caustic rust removers.
A few months after I sold my first horse, I was walking through the pasture and found a shoe he’d lost sometime in the year before. Looking at it, I thought it would be a nice keepsake- and something I could use to create an equestrian project with sentimental value- but it was covered with layers of rust.
I’d been experimenting all winter with using citric acid to clean rust off garden tools that I, in my distractability, tend to leave out in the elements. As it turns out, the basic combination of citric acid, water, and time completely removes rust from metal. I was pretty thrilled, especially after trying and mostly failing to remove rust from tools with caustic chemicals. A common ingredient in canning recipes, citric acid is an organic acid a little stronger than vinegar, depending on the concentration you mix it in.
2021 Update: I’ve loved reading your feedback on this article and how many of you have found this tutorial useful! A lot of the comments have suggested replacing citric acid with vinegar and soaking a little longer, and I wondered it this would work as well, so I recently did some experiments. At the bottom, you’ll find a price breakdown (spoiler: there’s a clear winner) and some important safety information on using alternative household chemicals other than the very safe one described in this tutorial below.
Supplies You’ll Need for No Scrub Rust Removal:
- A bucket or plastic container large enough to hold your rusted object(s)
- Very hot water
- A surface treatment for raw metal. Oil or clear coat varnish works.
- Pure Citric Acid – You can buy this wherever canning supplies are sold, however, the pricing on citric acid sold for canning includes a huge markup. As of spring 2021, Ball brand citric acid is priced over $1/ounce but a 5 lb bag of food-grade Citric Acid is 25¢/ounce.
My advice is to order in bulk and don’t worry about having too much – it’s SO handy for cleaning! A tablespoon of Citric Acid is great for boosting dishwasher detergent, descaling coffee makers, getting grime off pots and pans, removing hard water stains, and general cleaning. You can use it in cooking too- soaking cut apples in a weak citric acid solution to prevent browning, or adding a tablespoon to bone broth at the beginning of the cooking process to help break down bone and transfer nutrients into your broth.
Prepare Acid Bath
Fill your bucket with very hot water and stir to dissolve the citric acid powder completely into the water. There should be no grit remaining at the bottom of the bucket.
Submerge Rusty Item in Solution
Allow Rusty Object to Soak
Continue soaking your object until you see visible results. Some items will be rust free in hours, while others may take a full day or multiple soaks. After a day you may want to remix your citric acid solution, because it will slowly lose acidity as it breaks down the rust. If you are a fan of instant gratification as I am, you may want to do a bit of scrubbing to speed the process.
Speed the Rust-Removal Process with an (Optional) Scrub
The above image is how my rusty objects looked after 2 hours in the solution and a quick wipe with a paper towel.
Remix & Resoak if Needed
When finished, the solution is safe to discard down a drain- the chemical reaction that dissolves the rust will have neutralized the acid, making it harmless for most household pipes (if any pieces of rust have broken off and settled at the bottom of the bucket, do NOT put these down a drain, and instead discard in the garbage).
Seal the Rust Free Metal
IMPORTANT: You MUST protect the finish. If left uncoated, the unprotected metal will rust again almost instantly. To prevent new rust from forming, You can apply clear coat / lacquer, spray with cooking oil and wipe away the excess, or jump over to my tutorial for creating an antique gold finish (which looks great AND prevents rust).
Scrubbing is optional but speeds the process up significantly. The acid will loosen before it completely dissolves the rust, so much of the rust can be effortlessly wiped off after an hour or two in the solution.
In this photo you can see the yellow-tinge the solution takes on as it is working, as well as the loosened rust sediment that will settle in the bucket.
If you’ve cleaned up a keepsake horseshoe or bit, I have a few tutorials on how to display them:
2020 Update: Vinegar vs Citric Acid
Since published, this article has traveled far and wide and collected a lot of feedback comments- many advising to “just use vinegar” was a comparable technique. Recently, I decided to do a side by side comparison of vinegar vs citric acid in my kitchen. Without repeating the entire rust removing process (difficult to compare with scrutiny, since no two objects rust exactly alike) I ordered some pH testing strips.
To be the “better” rust-removing solution, the winner would need to be 1. higher in acidity, 2. lower in cost, or 3. both. My suspicion was that citric acid would win by a landslide, but my experiment progressed.
I mixed one cup of citric acid solution at the concentration recommended above (.33 cup per gallon, or in this case, the ratio scaled down to 1 tsp citric acid to 1 cup water) and tested it against a leading name brand of undiluted white vinegar.
RESULT #1: ACIDITY
At the recommended dilution, Citric Acid solution is slightly more acidic than vinegar– matching the scale in my pH testing kit at a pH of 3, compared to the name brand distilled white vinegar at pH 4. (Interestingly, according to the internet, the pH of distilled white vinegar should be between 2-3, meaning either my name-brand vinegar was weak or, more likely, my pH testing kit was not lab-accurate. Even if this is the case, I anticipate the values relative to other values read by the same test strips should generate accurate comparisons)
But how do they measure up in terms of cost? Read on
RESULT #2: Cost of Vinegar vs Citric Acid
For one gallon of cleaning solution (just enough to clean an average-sized tool or a few horseshoes), you need either 1 gallon of vinegar or 1/3 cup of citric acid mixed with tap water. (To make the math easy, let’s say .5 cup of powered citric acid)
At major grocery outlets, a gallon of vinegar seems to run about $3-$4.
Currently, citric acid powered in bulk (5lbs) is $15 for 5 lbs. Citric Acid powered weighs about 2 cups per pound. The 5 lb bags, then, contains 10 cups, resulting in a cost of roughly $1.50 per cup of powder. The one half of a cup required to make a gallon of rust removing solution, then, comes in at right around 75¢
Therefore, rust treatment with citric acid costs less than 75¢ per gallon, while the same process with white vinegar costs $3-$4 per gallon. Given that the citric acid solution is stronger, and thus faster acting, it’s the better choice for rust removal through no-scrub soaking.
If you loved this tutorial, Support Hawk Hill by making a coffee-sized donation.
Using Citric Acid to Remove Rust from Things that can’t be Soaked.
While this tutorial is a low-effort and speedy way to remove rust from tools without scrubbing, it has its limitations. large and bulky objects cannot be dropped into a bucket for soaking.
Recently, I ran into this problem in Hawk Hill Cottage, and I came up with a solution worth adding as an update to this post. The cottage features only one full bathroom, but oh, it is a glorious bathroom! A large skylight opens up over the shower to add a view of the sky and swaying trees visible from the shower. Recently updated and clean bright white, the only eyesore in this bathroom was an ugly red rust stain in the bathtub.
Even the professional cleaner hired to clean the cottage before I moved in couldn’t get this ugly red stain out of the tub. I was determined, however, that I would. So I set out to experiment with various cleaners.
I won’t run through my laundry list of tub and tile cleaners I tried on my bathtub’s rust stain, but suffice to say it was more than a few (and a lot of elbow grease!) Nothing even touched my rust stain.
One day, though, as I was reading the instructions on the bottle of Bar Keeper’s Friend Soft Cleanser, I noticed that citric acid was listed among the primary ingredients. I wondered: “Could this be my solution?” Bar Keepers Friend, since it is a thick, viscous liquid, might stay in place when dabbed on the stain (rather than running off like a liquid or immediately drying like other cleaners).
Excited to try my theory, gloved up and poured a small pool of bar keepers friend onto my tub’s rust stain one night before bed. I didn’t scrub at all, I just dumped a small amount of this citric acid-containing cleaner directly on the stain and hoped for the best.
The next morning- I won’t like- I woke up excited to clean my shower! (That might be a first for me) I grabbed a small scrubber and began gently scrubbing away the crust that Bar Keepers Friend had dried into overnight. To my delight, I found that the ugly red rust stain had entirely dissolved overnight after being soaked in the cleaner containing citric acid. I never even had to scrub except for the bit of elbow grease required to remove the dried cleaner from the tub.
Unfortunately, since I tried this project on a whim- without much hope of success, I didn’t document this rust removal success, but you can bet I’ll have my eye out for a rust stain to demonstrate how a viscous cleaner containing citric acid can remove rust from surfaces that can’t be soaked.