Cleaning Floors Before Concrete Staining: Tips from the Pros
Proper floor preparation is the first step in creating
beautiful concrete floors like this one. Diamond D
Company in Capitola, CA
Any materials that inhibit concrete stain
penetration, such as grease, oil, or curing
membranes, will prevent the color from taking.
Questions to Ask When Selecting a Remover or Cleaner
Once homeowners see how beautiful and easy to maintain decorative stained concrete floors can be, they often are eager to rip up their grungy carpets and yellowed vinyl tiles to expose the concrete underneath. These enlightened homeowners have become a significant market segment for stain applicators. But those newly naked floors often need extreme cleaning before they can be adorned with chemical stains.
"We're seeing a lot of remodeling going on, and that's a lot different from new floor staining projects," says Barbara Sargent of Kemiko Concrete Products, Leonard, Texas. "When you pull up carpet or tile, you never know what you might run into. Carpet glue, tile mastics, water and urine stains, chalk marks, caulk, grease stains, paint drips, and rust spots are just a few of the contaminants that staining contractors have encountered," she notes.
The Importance of a Clean Surface
"If you are negligent in the cleaning process, it can literally change the entire end effect. A substandard cleaning job will really show up once the final sealer or wax is applied," says Sargent.
"Chemical stains also need to penetrate into the concrete surface to react with the lime in the concrete. Any materials that inhibit concrete stain penetration, such as grease, oil, or curing membranes, will prevent the color from taking, says Tom Schmidt of Jagger Scored/Stained Concrete, Plano, Texas, a company specializing in decorative staining of residential and commercial concrete floors.
Schmidt also warns against acid etching of floors before staining. A lot of people think they need to acid etch the concrete like they do before applying a paint or coating, to get the paint to adhere. But acid washing depletes the lime content, which is what the minerals in the acid stain react with.
Trial and Error
However, finding the right cleaning product is often a trial-and-error proposition, she admits. You can't always tell what a stain on concrete is by appearance alone. What you may assume is an oil-based stain may be something else. We recommend that contractors test products first to verify their effectiveness.
Precautions When Using Chemical Strippers
If the chemical stripper you're using is not environmentally safe, it must be disposed of properly. We retain the product in plastic buckets and then take the buckets back to our warehouse, where we put them into a hazardous waste container for disposal, says Schmidt.
For general-purpose cleaning and degreasing, Schmidt sweeps the floor and then scrubs it thoroughly using trisodium phosphate (TSP). For scrubbing, he recommends using a rotary floor scrubber with a green Nylo-Grit pad designed for aggressive scrubbing of concrete. If he must remove glue, mastic, or paint from the floor, he uses nonflammable chemical strippers, which he finds at Home Depot, Lowes, or Sherwin-Williams.
Bob Harris, president of the Decorative Concrete Institute and author of Bob Harris Guide to Stained Concrete Interior Floors, says caulking compound and mastic are two of the most difficult substances to remove. He scrapes off as much material as possible using a putty knife or floor scrapper and then applies a poultice to remove the remainder. For a poultice, he recommends mixing an inert fine powder, such as fly ash or hydrated lime, with denatured alcohol to make a smooth paste. Once the poultice dries, the caulk or mastic residue usually is brittle enough to remove with a stiff-bristle brush.
After using degreasers, chemical strippers, or other cleaning compounds, it's necessary to clean the floor again to remove all residue. Schmidt scrubs the surface once again with TSP followed by a thorough rinsing with clean water.
After the final rinsing, Schmidt often uses an industrial wet vacuum to remove all water and debris. If you just use a mop for the final wash, you're simply moving the residue around. he says, adding that using a wet vac also helps the floor dry out much faster.
When All Else Fails
Anne Balogh writes feature articles each month for The Concrete Network. She is a freelance writer based in Glen Ellyn, Ill., and a former editor of Concrete Construction magazine.
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