Things You'll Need
Distilled white vinegar
½ lb. sulfamic acid
Stiff nylon brush
Tile cleaner or grout haze removal product
Grout efflorescence is the whitish haze on tiles after installation. It generally does not come off with the initial cleaning of the tiles immediately following installation. Efflorescence in grout occurs when salts in the grout leach through to the surface of the tile. Although efflorescence can be removed from the tiles, you should wait at least 3 days after installation before applying water, and at least 10 days before applying any products containing acid. This will give the grout ample time to cure. You can effectively remove grout efflorescence from tile by using the proper methods and products.
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Step 1: Removing Efflorescence With Vinegar
Use distilled white vinegar to remove mild grout haze. Apply undiluted vinegar to the tile with a rag and wipe the efflorescence from the tile. Follow this by cleaning the tiles with soapy water and drying thoroughly with a clean towel.
Step 2: Sulfamic Acid and Water
Mix ½ lb. of sulfamic acid crystals into a bucket with 1 gallon of hot water for tougher efflorescence grout stains. Sulfamic acid is a product that is readily available at most home improvement centers.
Step 3: Soak With Water
Use a clean sponge to soak the affected area with plain water. Allow the plain water to sit on the tile for about an hour.
Step 4: Apply the Acid Solution
Use dry towels to soak up the water from the tile. Pour the acid solution onto the tile so that it forms puddles in the joints.
Step 5: Scrub the Tile
Scrub the tile with a stiff nylon brush. Let the acid solution sit on the surface for about 5 minutes, then scrub the tile again.
Step 6: Wipe and Dry
Wipe up the acid solution with rags dipped in clean water. Dry the tile thoroughly with a clean towel.
Step 7: Use the Tile Cleaner
Apply a cleaner specific to the type of tile you are working with or a grout haze removal product. Follow the manufacturer's specific instructions for application.
Step 8: Substitute Phosphoric Acid if Necessary
Substitute phosphoric acid for sulfamic acid if the efflorescence in the grout is really bad. Phosphoric acid is a stronger chemical than sulfamic acid and will be effective at removing more troublesome cases of grout efflorescence. Mix 1 part phosphoric acid into a bucket with 5 parts plain water. Apply and clean up the solution in the same manner used with the sulfamic acid. Follow up by cleaning the tiles with an appropriate tile cleaner for the specific tile you are working with.
Wear rubber gloves, protective eyewear and long sleeves and pants when working with products containing acid. These chemicals can cause serious injury to your body.
Never apply acid to the tile without wetting it first. The tile may sustain burns from the acid if it is not thoroughly wetted prior to applying.
Test the product you are using on a small inconspicuous area of the tile prior to applying it throughout. Look for any discoloration or damage the product may cause to the tile.