How to Properly Use Phosphoric Acid for Rust Removal

Rust or corrosion is a nuisance no one likes or tolerates in their homes. People dislike rust because it causes metal objects to decay, and it can be rather dangerous since it can cause tetanus if the person gets injured while handling a rusty object. Therefore, some are trying to get rid of it any way they can — and a few are even using phosphoric acid for rust removal.

Although this solution is rather effective when it comes to rust removal, there are many factors you should consider before using it. You need to get acquainted with phosphoric acid in order to use it properly and protect yourself and others from potential injuries.

And that’s exactly what I’ll be talking about today. If you plan on using this solution for rust removal, here’s how to apply it properly and in a safe manner.

How to use phosphoric acid for rust removal.

How to Stay Safe When Using Phosphoric Acid for Rust Removal

Before I move on to some tips, I do have to explain what phosphoric acid is. By definition, it is a mineral acid without any color or smell that’s used in many different industries. You can even find it in some foods and drinks, including everyone’s favorite soft drink, Coca-Cola. However, despite its popularity, you have to keep in mind that it’s rather dangerous if not handled carefully and responsibly.

Go Outside When Using Phosphoric Acid

Before you apply phosphoric acid on a corroded object, make sure you are outside. When it comes into contact with corrosion, this chemical releases fumes that could potentially be dangerous if you inhale them. Handling phosphoric acid in a well-ventilated room or outside will definitely reduce the risk of inhaling the poisonous fumes.

Use Proper Equipment When Handling the Chemical

You should know that, in case of contact, phosphoric acid can cause severe damage to your skin, eyes, mouth, and respiratory organs. Therefore, you must always wear protection when handling this chemical.

Here’s what you simply must wear when removing rust with phosphoric acid:

  • A face shield or safety goggles
  • Protective gloves
  • Long sleeves
  • Regular pants (avoid short pants as they expose a lot of skin)

How to Properly Apply Phosphoric Acid on a Corroded Object

In order to get the best results and remove rust from an object, you have to know how to apply this chemical properly. Doing it haphazardly will not only provide you with mediocre results but possibly endanger your health. So, here’s how to eliminate rust but still stay safe while using the acid.

Use a Paintbrush to Apply the Acid 

When you buy phosphoric acid for the purpose of rust removal, the solution usually comes in a can in the form of a jelly. Therefore, the best way for you to apply it is by using a paintbrush. Cover the object with the jelly, even the parts that are not corroded. That way, you’ll protect the rust-free areas from potential corrosion.

Once you cover the object with jelly, let it sit for an appropriate amount of time. You will see precisely how long that is in the manufacturer’s instructions. Usually, you’ll have to wait for about five minutes.

Scrub the Rusty Parts

When you’re done waiting for the jelly to do its magic, make sure to scrub the rusty parts with some steel wool or wire brush. In case the rust is persistent, leave the jelly to sit for a few more minutes and then scrub it away.

Clean the Object With Water

Take a garden hose, step away from the object, and rinse it with water. Make sure the acid doesn’t get onto your skin. Then, coat the metal object with baking soda, scrub it with a brush and rinse it with water once again.

Once you do all of this, leave the object to dry outside. This should be enough to remove the rust.

Related post: How to Use Naval Jelly to Remove Rust

What to Do If You Come Into Contact With Phosphoric Acid Jelly

As mentioned earlier, this solution can cause some rather nasty health problems, so it’s paramount that you prevent it from touching your skin, mouth, or eyes. However, if this does happen, you must stay calm and do the following:

  • If you inhale the fumes, find some fresh air and seek attention from your doctor.
  • In case it gets into your eyes, wash them and go to the hospital.
  • If it touches your skin, rinse it with water and go to the doctor’s office.

In case you come into contact with phosphoric acid, it’s important that you get help as soon as possible. Don’t wait to see if the wounds will get better. If you act fast, you will be able to avoid further harm and treat the wounds properly.

Final Thoughts

Even though using phosphoric acid for rust removal is one of the best ways to get rid of corrosion, you must be careful when handling it. If you don’t use it properly, you might get severely injured. Therefore, follow the instructions thoroughly and use the recommended protection. And in case you are so unlucky that you do come into contact with the acid, get yourself to the hospital as soon as possible — the doctors will know how to help you.

1 thought on “How to Properly Use Phosphoric Acid for Rust Removal”

  1. Hi there, im currently doing some rust removal on my cars subframe, i have what i think is either phosphonic acid or phosphoric acid in white granular form (just like rock salt) and i was hoping you could tell me the best way to apply it to remove the rust. ( i cant dip the part it is too big) what i have done so far is mix it with water and dab it onto the part with a brush and it works ok. im just hoping you have a better method of applying as its pretty messy this way.

    thanks for reading

    kind regards


Leave a Comment