How to Prepare a Concrete Floor for Painting

Concrete floors need to be prepared before you paint them so that the paint adheres to the concrete. Once the floor is cleaned and cracks are patched, a porous surface is created by etching the surface. Without this porous surface, the paint will quickly start to peel and wear off. Etching is done with an acid solution, so be prepared to wear safety gear in a well-ventilated area or wear a mask if you're working in a closed room. Working with acid is dangerous. Be careful.

Things You'll Need

• Broom Vacuum Bleach Stiff brush Mop Mortar Trowel Muriatic acid Rubber gloves Goggles Ventilating mask

Instructions

1. 

   Sweep the floor thoroughly. Remove stuck-on materials like chewing gum or stickers, then vacuum the floor.

2. 

   Mix a solution of 50 percent water and 50 percent bleach. Ventilate the room. Scour the floor with the solution and a stiff brush. Mop up the dirty solution and then rinse the floor with fresh water. Allow the floor to dry completely.

3. 

   Repair cracks or divots in the floor by floating mortar into the cracks and smoothing it out with a trowel or the tip of your finger. Use a damp sponge to wipe up excess mortar. Let the mortar dry thoroughly and then sweep again.

4. 

   Combine 3 qt. of water with 1 qt. of muriatic acid in a bucket. Put on rubber gloves and safety goggles and make sure the room is well ventilated.

5. 

   Use a stiff brush to work the solution into the floor. The solution will bubble. Wait until it stops bubbling and then rinse the floor several times. Mop up standing water.

6. 

   Let the floor dry. Vacuum up the white powder that the muriatic acid will leave on the floor once it's dried. Use a damp mop to clean up any of the powder that remains after vacuuming.

Tips & Warnings

• A gallon of water and muriatic acid solution will cover 100 square feet. Buy muriatic acid at home improvement stores.

• Always add acid to water, never add water to acid. A chemical reaction will occur, causing the acid solution to splash out of the container. Read all of the manufacturer's instructions. Acid is dangerous.

Resources

• Working with Muriatic Acid
• Different Concrete Painting Techniques
• How to Paint Concrete Floors