How to Acid Wash Your Concrete or Garage Floor

concrete floor
  • 5-10 hours
  • Intermediate
  • 250-500
What You'll Need
Muriatic acid
Several gallons of ammonia
2 gallon lastic watering can
Hose connected to the water supply
Boots (plastic)
Rubber gloves
Filtered mask
Wire brush
Push broom

Hiring a professional to acid wash your concrete or garage floor can be quite expensive, especially for a job you can do yourself. If you want to clean your garage of oil spills or lay down a coat of stain, acid washing your floor is the best first step to a great finished project. Follow these easy steps to acid wash your concrete or garage floor.

Step 1 - Clean the Surface

In order to achieve the perfect finished project, you must first clean the floor which you plan to acid wash. Remove everything from the surface and sweep away the dirt. Hose the surface in order to remove any tough particles. If there are any oil stains on the floor, remove them with the proper cleaner. When you are done cleaning with chemicals, it is always a good idea to rinse the floor one last time with water.

WARNING: Even if you rinse the floor with water, the cleaning products you use may leave residues that will react with the acid in dangerous ways. Research what cleaning products react with the kind of acid you'll be using, and plan ahead.

Step 2 - Create a Barrier

If you are planning to acid wash near asphalt, drywall, or tarmac, then it is important to create a barrier. The acid that you are going to use can damage any of these materials. You can use a tarp, plywood, or stones in order to block the flow of acid and water.

Step 3 - Mix the Muriatic Acid

The acid will be mixed directly in a plastic watering can. The standard ratio is 1 part muriatic acid to 4 parts water. You can increase the strength of the acid mixture to 1 part acid to 2 parts water if need be. Make certain you are mixing acid to water and not water into acid, as the mixture can become volatile.

TIP: Research the acid you choose to use and find out whether it will be easy to handle and what kind of safety gear you'll need as a result. Muriatic acid is one of the stronger acids, so you'll need lots of caution and safety gear (rubber boots or coveralls, respirator mask, safety goggles and thick gloves)

Step 4 - Apply the Acid

Before you can apply the acid wash to the flooring, you have to first lay a layer of water. Spray the floor with water until it's completely wet. Use a push broom to brush away the water, as you don't want puddles of water. The surface just has to be covered with a thin layer.

You can now put on the protective gear and walk around the wet floor with the watering can, applying the acid and water mixture. The water should bubble and be yellow in color. If it is not yellow, then the surface is sealed and you will have to remove the sealant before acid washing the floor. Use the broom to push the water and acid mix around the floor. When the bubbling has stopped, you can dump the ammonia onto the floor in order to neutralize the acid.

Step 5 - Finish Up

It is now time to finish the acid washing of the floor by rinsing away the chemicals with pure water. Allow the surface to dry prior to applying any coating.