Acid Washing and How to Do It?

close up of a bottle with cleaning instructions on the label

Introduction to Acid Washing

Acid washing has emerged as a pivotal process in numerous industries, ranging from construction to manufacturing. This method, which involves the use of acid solutions to clean surfaces, is especially popular for its effectiveness in removing stains, cement and grout residue, scale, and rust that conventional cleaning methods can’t tackle. Furthermore, acid washing can significantly improve the longevity and performance of treated materials such as brick, cement and tiles.

Understanding the Essentials of Acid Washing

Before diving into the acid washing process, it’s critical to grasp the basics. Acid washing employs strong acids, such as hydrochloric or muriatic acid, which can aggressively react with the buildup of minerals, stains, or rust. It’s a process that demands respect for safety protocols to avoid damage to the materials being cleaned, as well as ensuring the well-being of the person performing the task.

Always remember, all surfaces including brick, cement and tiles are different so this is not a one acid wash fits all. Always consult with the manufacturer on the right type of acid was to use on a particular type of flooring. Acid wash can be extremely damaging to surfaces so it is imperative you use the right wash. 


Safety First: Preparing for Acid Washing

Safety cannot be overstated when it comes to handling acids. Before entering any site you will need to be prepared and have the appropriate personal protective equipment (PPE) – including acid proof gloves, goggles, and protective clothing – this is non-negotiable. Ensuring good ventilation and having neutralising agents at hand are also pivotal steps in prepping for a safe acid washing session.

Note: If you are a commercial or residential cleaner performing acid washing, you will also need to have the appropriate Saftey Data Sheets and Saftey Work Method Statements.

Materials and Tools Needed for Acid Washing

  • Hydrochloric or muriatic acid
  • Water
  • Plastic or glass containers
  • Mop and bucket
  • Wet and dry vacuum cleaner (optional)
  • Acid-resistant brushes or scrubbers
  • Neutralising agent (such as baking soda)
  • Protective gear (acid and tare-resistant gloves, goggles, and protective clothing)
  • SDS, or Saftey Data Sheets
  • SWMS, or Safe Work Method Statements. Don’t have a SWMS? You can learn more here and download your free pdf.

Step-by-Step Guide to Acid Washing

Now, let’s delve into the detailed step-by-step guide to acid washing, which if followed meticulously, can yield exceptional results.

Step 1: Surface Preparation

Start by cleaning the surface by either sweeping or vacuum, was the surface with water to remove any loose debris or dust. This initial step ensures that the acid can work directly on the tough stains or scales without interference.

A picture of a yellow Karcher vacuum preparing and vacuuming a tiled floor with debris scatted on the floor

Step 2: Mixing the Acid Solution

In a plastic or glass container, carefully mix the acid with water. Always add acid to water, never water to acid, to prevent a violent reaction. The typical ratio is one part acid to four parts water (1:4), but this can vary depending on the strength of acid needed. Some floors might need a 1:1 ratio and some might need a 1:20 ratio.  This will vary depending on how stained the floor is.

a close up of two bottles mixing the two liquids together in preparation

Step 3: Applying the Acid Solution

With your protective gear on, apply the acid solution to the wet surface spreading the solution evenly across the area. Use an acid-resistant brush or scrubber to spread the solution evenly. You can find an assortment of brushes and scourers at your local Bunnings warehouse. 

Tip: Always test the solution first on an inconspicuous spot.

A bottle of acid wash solution and red rubber gloves on a dark tiled floor

Step 4: Scrubbing

Gently scrub the surface with the brush or scourer to help the acid work into the stains. Do not use metallic scrubbers as they can react with the acid. Assess after gently scrubbing and if it is safe to do sp you can apply pressure to really scrub away any stubborn stains.

a close up of a cleaner wearing red rubber gloves scrubbing a tiled floor with acid wash

Step 5: Monitoring the Reaction

Keep a close eye on the reaction between the acid and the surface. You’ll typically see bubbling, which indicates the acid is reacting with the minerals or stains. Most acid washes can be left from anywhere between 5-15 minutes. Also keep checking! It is better to measure twice and cut once.

close up image of acid wash solution on tiled floor bubbling from cleaning effects

Step 6: Neutralizing the Acid

Once the bubbling has subsided, it’s time to neutralise the acid. Sprinkle a neutralising agent, like baking soda, over the surface and rinse thoroughly with lots of water.

a tiled floor with a white toilet covered in acid wash ready to be washed and cleaned dry

Step 7: Rinsing the Surface

Rinse the surface multiple times to ensure no acid residue remains. This step is crucial for safety and to prevent any potential damage to the material. To remove large amounts of solution you can soak up the solution is cloths or towels, squeege into a dust pan or vacuum up using a high quality wet and dry vacuum.

You can see some of the best wet and dry vacuums for vacuuming up liquids here

A hand wearing a red rubber glove wiping a tiled floor dry with a yellow microfibre cloth

Step 8: Inspecting The Surface

After rinsing, inspect the surface. If stains or scales are still present, you may need to repeat the process. 

Tip: You may want to just directly attack stubborn stains so you aren’t going over your work twice. Soak the stain, cement residue in the solution, leave it, then rinse repeat.

Step 9: Drying and Final Touches

Allow the surface to dry completely. If you’re acid washing metal, consider applying a rust inhibitor to prevent future corrosion. Come back once the surface is completely dry to asses if there will be another application.

Aftercare and Maintenance

Post-acid washing care is paramount to maintain the pristine condition achieved. Regularly clean the surface with mild detergents, brooms, scrubbing brushes and schedule periodic inspections to catch any issues before they become significant problems.


By adhering to this comprehensive 9-step guide to acid washing, one can attain unmatched cleaning efficiency. The process, although meticulous, can drastically improve surfaces’ aesthetics and functionality when performed correctly. Embrace the power of acid washing to outshine and outlast the rest.