HOW TO ACID WASH CONCRETE – Concrete is very porous and stains easily if it is not treated with an epoxy coating. The garage floor tends to be one of the most vulnerable areas with oil, grease and dirt stains soon becoming apparent on newly laid concrete. Sometimes the only way to clean it is by using an acid wash – in the guide below you can learn how to acid wash concrete properly and more importantly safely.
It is also interesting to note here that Acid Washing can, and does an awful lot, be used to create decorative patterns to a concrete floor. Watch the video above for details.
Step 1
The first thing you need to do is to purchase some muriatic acid from your local DIY store. Acid, by its very nature burns and produces toxic fumes so you MUST prior to handling the acid wear protective clothing, eye wear, gloves and footwear. When applying the acid make sure the area is also well ventilated and that you wear a face mask.
Step 2
Depending on how you want to wash the concrete floor you need to follow the manufacturer’s instructions exactly. Mixing and application instructions may vary so do follow these carefully for effective and safe application.
Step 3
Clean the area thoroughly before starting the job. Sweep up any dust and debris. The cleaner the area is the easier the job will be.
Step 4
If you are acid washing a large area of concrete then it is advisable if you have help. Take the mixture and pour this into a spray applicator. Spray the concrete floor, working from side to side as you work your way though the entire area. As you spray use a broom to scrub the floor. You may find that the broom leaves marks and to prevent the marks from remaining, simply spray of the marked areas and do not scrub the area again.
Step 5
Once you have covered the entire areas leave it to dry. Depending on the type of acid wash you are using, some areas may appear darker or a different colour. Concrete is very porous so this is natural and you will find that the colouring will change as it dries out.
Step 6
Before the area is completely dry you need to stop the acid reaction. Take a large mop and bucket and fill with water and add baking soda. The baking soda will neutralize the acid reaction and you need to completely saturate the floor. Move the mop around cleaning as you go. This process, as stated neutralizes the acid and remove the acid residue on the surface of the concrete.
TIP: Don’t walk across any area that you have not mopped – start at one end and work your way across. If you do walk from the area you are mopping to an area that has not yet been mopped you can leave footprints in the acid that will show up in the final stage.
Step 7
You can now clean off the water from the surface using a commercial Wet Vac. These can be hired from most tool hire companies – just let them know what you are doing so that you get a machine that is capable for the job.
IMPORTANT: Do NOT let the acid wash solution enter the storm drains. You should collect any run off water and dispose of it at your local recycling center.
Step 8
After you have completed the cleaning as in Steps 6 & 7 above you may have to repeat this if acid residue is still evident. You need to remove any acid as this will degrade the concrete floor over time, so ensure that all acid residue has been completely cleaned off the surface of the concrete floor. To make life easier make sure you change the water in the bucket often to ensure you have clean fresh water going onto the floor.
Step 9
Once cleaned you need to leave the floor to dry completely. This can take 24 to 48 hours. A trick here is to place floor fans in the area to help it dry. Once the floor is completely dry you can apply a sealant coating to the floor.
