How to remove rust

Do you have tools or other metal objects that have started to rust? Then you’re not alone. Rust is a common problem that occurs when iron reacts with oxygen and water. Fortunately, there’s a simple, environmentally friendly, and effective way to remove rust using citric acid. In this guide, we’ll show you how to save rusty objects at home using just a few ingredients.

 

How to remove rust with citric acid—step by step

1. Mix a bath
Pour warm water into a bowl and add 4 tablespoons of citric acid per liter of water.

 

2. Place the objects in the bath
Place the rusty objects in the bath. Leave them for at least a few hours, preferably overnight.

 

3. Rinse and scrub
Once the rust has come off, rinse with water and clean with soap and a soft cloth or brush.

 

4. Protect the metal
Dry the objects completely. Brush them with cooking oil and heat them in a frying pan to create rust protection.

 

5. Wipe dry and store in a dry place
Let it cool, wipe it off with a cloth, and store it in a dry place.

 

Scroll down for a complete guide with before-and-after photos and more tips!

 

 

First, let’s clarify the terminology!

 

What is rust?

 

Rust is “flaky,” porous iron hydroxides that contain water. Rust is usually reddish-brown. Rust forms when  iron corrodes—in other words, rusts. For something to rust, water and oxygen are required. Because rust is porous, it does not protect the underlying iron from further corrosion; instead, it causes the iron to rust even faster once the process has begun.

 

Rust forms in two stages. First, red rust develops; it is light reddish-brown and less serious. This rust can often be removed. We’ll show you how! But if red rust is left in place, it eventually becomes pitting corrosion, which is dark brown or black. Pitting corrosion is hygroscopic, meaning it absorbs moisture, and in the presence of moisture, the corrosion penetrates deeper. The strength of the affected object deteriorates rapidly.

 

We’re now going to see whether we can remove ALL the rust from these pliers?

 

 

The pliers are affected by both surface rust and deep pitting corrosion. You might think we need something very strong, but with a little basic chemistry, that isn't necessary at all. We need an acid—and ordinary citric acid is enough.

 

Citric acid is added as an antioxidant in products such as juice and jam and appears in ingredient lists as E330. Citric acid is also used to preserve vitamins in food. Its chemical formula is C6 H8 O7. So, citric acid is acidic but not dangerous; as its name suggests, citric acid occurs naturally in lemons.

 

Here, we have placed the tongs and the small bell in a bath of water and 4 tbsp of citric acid. As you can see in the image below, the surface rust disappears immediately, but because these items are heavily affected, they are left in the bath.

 

 

Below, you can see the bath after two days.

 

 

The loose rust lies at the bottom of the bowl.

 

 

The items are now free of rust, and we clean them with soap and an eco-fiber cloth to remove the citric acid and the remaining rust, which has now loosened.

 

 

Here you can see how deeply the tongs have been affected by rust in places.

 

 

To protect the items from future rust attacks, we place them in cooking oil and heat them in a frying pan briefly at high heat. Once they have cooled, we wipe them clean with paper or a cloth.

 

 

Blackening is a method of preventing rust. The process involves heating the metal in question (often iron) to approximately 300°C and then applying linseed oil. This protects against rust and gives the iron a deep black surface, which is why it is called “blackening.” Here, we used ordinary cooking oil (rapeseed oil) instead of linseed oil.

Before

 

 

After

 

 

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Questions and Answers

 

- Why are water and oxygen needed for iron to rust?
Rust formation requires both water and oxygen. Water enables the corrosion reaction by acting as an electrical conductor, while oxygen is part of the chemical process.

 

- How can you remove surface rust from an item?
Surface rust can be removed using an acid, in this case citric acid. The citric acid reacts with the rust and dissolves it from the surface.

 

- What is hygroscopic rust, and why is it dangerous?
Hygroscopic rust, such as deep-seated rust, is dark brown or black and can absorb moisture from the surrounding environment. This allows the rust to continue attacking the item more deeply and rapidly, weakening it.

 

- How do you protect items from future rust attacks after cleaning them?
After cleaning, the items are treated with cooking oil and heated in a frying pan to create protection against rust. This forms a barrier between the metal and moisture, preventing corrosion.

 

- What is blackening, and how is it carried out?
Blackening is a rust-prevention method in which the metal is heated to approximately 300°C and then treated with linseed oil to give it a deep black surface. In this case, ordinary cooking oil was used instead to achieve similar protection.