How to Acid Wash Concrete

Using a muriatic acid wash is the solution of last resort for cleaning stubborn stains and blemishes from concrete. The acid works by dissolving the concrete to remove the stain and it can permanently damage concrete if mishandled.

Difficulty: Challenging

Instructions

Things You'll Need:

• Muriatic Acid
• Muriatic Acid
• Protective Clothing
• Protective Clothing
• Water Source
• Pressure Washer
• Power source (electric or gas)
• Eye protection
• Vessel to collect hazardous runoff water
• Latex or rubber gloves

1. Try every other means available to remove stains from concrete before using muriatic acid. (See Related eHows.)

2. Purchase muriatic acid from a home improvement retailer or a chemical wholesaler.

3. Put on protective clothing and gear before handling the acid, including goggles and rubber or latex gloves.

4. Read the manufacturer's application directions carefully and follow them exactly. Apply only as much acid as needed, no more, and let it soak into the concrete surface for several seconds.

5. Rinse the acid off the concrete with water using a pressure washer set at 2500 to 3000 PSI and contain the resulting runoff so that it does not enter a storm drain.

6. Sprinkle baking soda over the area you treated with acid to neutralize the solution.

7. Take the runoff water to a recycling center that accepts hazardous materials.

8. Assess how much the acid damaged the concrete and consider resealing the concrete to prevent future stains or deterioration of the concrete.

Tips & Warnings

• Because of the dangers inherent to handling hazardous materials and the damage it can inflict on concrete, use muriatic acid only as a last resort. Although it may remove tough stains, the concrete may require significant repair after acid washing.
• Muriatic acid is extremely toxic. Handle it with caution and respect.
• Do not allow muriatic acid runoff to enter a storm drain where it will pollute water sources and kill marine wildlife. Locate a recycling center that accepts hazardous materials to dispose of the acid runoff.

[millerm8691]

on 5/31/2008 I used too much muriatic acid on my driveway. It continues to degrade more and more each day. How can I prevent this from continuing?

[ConcreteMan]

on 5/31/2007 Yes jagerbill is correct, the mixture should be a 50%/50% mix, we call this etching and NOT recommended for the average homeowner because one can really damage the concrete surface if inexperienced, or acid burn themselves. I recommend what I do every spring to my concrete work around my residence. Mix up a bucket of 50%/50% bleach and water and apply the same way; it cleans, brightens and removes those nasty leaf stains that occur through out the year.

[jagerbill]

on 4/18/2007 mix 50% acid, 50% water in a watering can (large). Add acid to water not water to acid. Keep your head away from the top of the watering can. Pour this mixture on the effected concrete and if necessary, use a stiff bristle broom to work the acid/water mixture into the concrete. Wait 5 min. and hose off the area. If needed, increase the acid to water water ratio and repeat the above steps. Always try this before using straight acid.