Clean with Oxalic Acid

Reiniging van een betonnen oppervlak met een hogedrukspuit waarbij oxaalzuur wordt gebruikt om roestvlekken te verwijderen.

Oxalic acid is known as an effective cleaner for challenging jobs. It can be used to remove rust and other stubborn stains from various surfaces, including buildings, boats, swimming pools, concrete paths, and wooden structures. In this article we provide information on how to clean with oxalic acid, explain how oxalic acid removes rust and provide some tips on how to protect yourself when cleaning with oxalic acid.

Preparing an oxalic acid solution

When you want to clean a surface with oxalic acid, it is important to first remove all dirt, grease and grit from the surface. After you have done this you can prepare an oxalic acid solution.

The substance oxalic acid occurs as a dry white crystalline powder. To make a cleaning solution, mix this powder with hot water. After you have done that, you can put the solution in a spray bottle and apply it to the surface to be treated. It is useful to rub the cleaning agent in with a brush or to let it sit for a while so that it can be properly absorbed into the stain.

Please note that heavy stains may need to be treated several times before the stain is completely gone. After cleaning the surface it is always important to rinse with plenty of water to neutralize the area.

How much oxalic acid should I use?

The amount you need depends on the application you want to use it for. To give you an idea, here are some suggestions:

  • For cleaning outdoor surfaces such as driveways, sidewalks and buildings, it is advisable to dissolve about 350 grams of oxalic acid per 5 liters of warm water.
  • If you want to remove stains from wood, you need a slightly higher concentration. For this it is best to dissolve 700 grams of oxalic acid per 5 liters of warm water. Apply the oxalic acid solution to the wood and allow it to take effect. If necessary, use a brush to ensure proper absorption. After it has been absorbed, rinse the surface well with water until no white residue is visible. If you want to sand the surface, make sure all the white residue is removed before you start.
  • You can remove rust with oxalic acid on metal surfaces by first cleaning the surface. The metal can then be immersed in an oxalic acid solution of 100 grams of oxalic acid per liter of water. The oxalic acid needs to work on the metal and it may need to remain submerged for a whole day to remove all the rust. After this is done you need to rinse and dry the metal.

How does cleaning with oxalic acid work?

Oxalic acid is known to be an effective agent in the fight against rust. It can remove stubborn stains where other cleaning products often fail. Below we explain the chemical reaction that takes place when oxalic acid reacts with rust.

When oxalic acid comes into contact with rust, a chemical reaction takes place. Rust (iron oxide) is converted into iron oxalate. Because iron oxalate is a water-soluble salt, it can be easily washed away.

What happens is that the iron in the rust bonds itself to the oxidized carbon in the acid to form the iron oxalate. The hydrogen and oxygen remain and together form water again.

The chemical reaction looks like this:

Fe 2 O 3 + 3H 2 C 2 O 4 -> Fe 2 (C 2 O 4 ) 3 + 3H 2 O

Safety precautions when cleaning with oxalic acid

Safely handling oxalic acid during cleaning operations requires strict precautions due to the potentially hazardous nature of the substance. As a powerful acid, it can cause serious skin irritation and is harmful if inhaled. Therefore, it is essential to wear personal protective equipment such as safety glasses, gloves and in some cases a respiratory mask , especially when working in poorly ventilated areas or when using high concentrations. Always provide adequate ventilation to minimize exposure to fumes. It is also important to avoid direct contact with the skin and eyes, as oxalic acid can cause irritation or even chemical burns. After use, any exposed skin should be washed thoroughly to remove residual acid. When mixing or handling the dry crystals, extra care should be taken to avoid inhalation, which can cause breathing complications. In addition, it is important to keep oxalic acid out of the reach of children and pets and to carefully follow the storage instructions. In case of accidental ingestion or exposure, seek immediate medical attention. These precautions are essential to work safely and responsibly with oxalic acid, an effective but potentially dangerous cleaning agent.

Where can I buy Oxalic Acid?

Oxalic acid is often available in buckets of 1 kg to 5 kg, or in bags of 25 kg. You can often find a solution of this substance in the hardware store, for example as a rust remover or wood bleach. For the pure crystal form of oxalic acid, with which you can make your own cleaning solution, you need to contact a chemical specialist. This pure is available at DutchChems. Visit our webshop for more information and purchasing options.