How to Clean Indoor Concrete (Part Two)



Rick Meehan

Vice President of Marko Janitorial Supply

Not all indoor concrete slabs are considered decorative, but the principle behind scrubbing them clean is the same. It is time consuming, hard work. It requires a level of expertise with equipment. It requires knowledge of cleaning chemicals and reactions with concrete. In short, it requires DACQAC, pronounced “Dack-Quack,” with explanations to follow. Remember the guiding rule from my last article, “Concrete Cleaning Inside-Out (Part One)”: a cleaning company must become a lean, mean, efficient cleanup machine. I will assume that your company is well on its way at this point to reaching this auspicious position. Therefore, we’ll jump right into the murky waters of indoor slab cleaning.

Whoa up thar pardner…thar ain’t no such thing as “jumpin’ in!” The moment you do is when you assume a loss, perhaps financially, but at the very least, of an opportunity to make some real dough. There is a list of variables – or, maybe I should say factors – that will determine the advisability of going forward with an indoor slab job. Here they are:

  • Differentiation
  • Assessment
  • Contemplation
  • Quotation
  • Acceptance
  • Completion

By following the rules of DACQAC, you will turn a profit in the realm of indoor slab cleaning.

The first task is to differentiate (D) between the types of indoor concrete surfaces. We’ve already taken a good look at decorative stained slabs, so what’s left? Many homes are built with slab subflooring. Bare concrete is sometimes found in basements. Carpet, wood, tile, laminate, vinyl, and other floorings can be hiding a slab until it comes time to change the covering. Identify the type of concrete: bare uncoated, cure-sealed, polyurethane sealed, acrylic floor finish sealed, slathered in adhesives (carpet glue, vinyl glue, and ceramic tile mastic), natural paste waxed, painted (latex, oil-base, and epoxy), decorative stained (acid stained, dye stained), stamped, non-decorative old or new concrete. It is important to make a correct determination, by asking questions of the homeowner, the installer, or your favorite supply house, about the exact type of surface you are dealing with, even if you think you already know. Each slab cleaning and/or recoating job is different and may require an array of chemicals, equipment, and cleanup processes to complete the tasks. [Follow the general procedure outlined in Part One.] Work with chemical supplier to obtain the right products for the job; seek proper training in chemical use. Differentiate (D) between the surface types and treat them accordingly to prevent mistakes. Here’s a general breakdown:




Bare Uncoated OLD

Most types of non-acid detergents may be used without harming the concrete, from neutral cleaners to degreasers. NO ACIDS (pH of less the 7.0) should be used unless prepping for paint, dye, stain, or glues. Acids change the surface – especially the color. If all other methods fail to remove a stain like rust or red mud, citrus-based cleaners or muriatic acid may be applied. The customer must be informed that this may change the appearance of the concrete in that area. Sometimes it is best to live with a spot than chance making the spot stand out more. All acids react with the calcium content in the concrete, even vinegar. Sanding and scraping methods used in resurfacing a slab are the next step beyond a thorough scrubbing with an appropriate detergent, but remember, we’re a contract cleaning company, not a specialty restoration crew (yet). As part of the contract, always offer to apply cure-and-seal or acrylic floor finish an add-on sale. Either of these coatings helps seal the concrete pores (all concrete is porous), add a shine, and protect the slab from further damage.

Bare Uncoated NEW

As with old concrete, avoid acid-based cleaning products. Keep all of the same information from above in mind, but consider too that changing the surface of new concrete, unless prepping for another non-clear coating, is taboo. That’s where lawsuits get filed. Unless your company is professionally trained in slab resurfacing (grinding, sanding), DON’T use acids! The best choice for new slabs is something like this: Marko SC100 All Purpose Neutral Cleaner.


Most concrete companies install a coating of Cure Seal Compound after their job is complete. This product used to be solvent-based, but now is available in acrylic-based finishes too. Both types are designed to soak into the surface of the concrete, filling the natural pores, protecting the slab from damage, slowing the drying time to make the surface harder, and leaving a temporary shine. Outside concrete is especially susceptible to damages from automotive grease, acid rain, heavy equipment, and wear from erosion over time. Indoor concrete gets the abuse of unprofessional homeowner cleaning tactics, food and drink spills, and common ablution products like nail polish, makeup, and rubbing alcohol.

Polyurethane Sealed

Think of polyurethane as a clear plastic surface. Concrete-rated polys come in many flavors, but serve the same purpose. They seal the slab, give a shine, last for years, and make the surface easier to clean. In a home, using a general purpose neutral cleaner, degreaser, or disinfectant within a pH range of 7.0—9.0 is sufficient. Rule of thumb: milder is better. Always use the mildest detergent that gets the job done. The drawbacks to polyurethane are encountered when refinishing or stripping is required. Polys usually have to be sanded off. The chemicals to remove them create hazardous waste as well as dangers to organic life. They are bad for you.

Acrylic Floor Finish Sealed

While not as permanent as polyurethane, acrylic floor finishes serve the same purposes. Like the stars of the sky, there are many qualities of acrylic finishes available. The cheap stuff doesn’t last long; the good stuff can last for years. You get what you pay for. However, it is even more critical that neutral cleaners ONLY are used for scrubbing these finishes. The homeowner should be instructed in proper care after the job, including materials to avoid. Acrylics are much easier to damage, but far easier to buff to a shine or apply new coats on top of the existing ones. Acrylics are more forgiving than polyurethanes.


Most glues, adhesives, and mastics can be removed with citrus-and-solvent-based cleaners, which soften them up, and then scraped away with a bladed tool. Paint removers containing MEK (methyl ethyl ketone), acetone, or alcohols may be necessary depending on the exact type of adhesive. Here again comes the issue of generating unwanted hazardous waste and carcinogenic materials.

Natural Paste Wax

The easiest of concrete coatings to remove, a standard wax stripper (pH 11-13) is all that is necessary. Follow the same procedure as stripping acrylic floor finish from a VCT or vinyl floor. This involves soak time, rotary machines, tank vacuums, mopping equipment, etc.


Paints include a wide variety of oil-based, epoxy-based, and latex-based products. Treat them the same as you would polyurethane coatings. Except epoxies, paints tend to be more easily damaged. They are softer than polys while tougher than acrylics in most cases. Milder detergents are recommended. Epoxies can be had in many qualities to withstand many thousands of pounds of pressure, so they rank in durability much like polyurethanes. Even strippers and degreasers (pH 10—14) can be used on most epoxies without fear. As with polyurethanes, removal of paints can generate unwanted hazardous situations. Beware of OHSA regulations pertaining to house remodeling. The fines can be huge, as in many thousands of bucks.

Decorative Stains and Dyes

Most decorative stains bond with the slab through chemical reactions, while most dyes are simply sprayed on to soak in while the concrete is curing/drying. Usually a clear coating of polyurethane or acrylic floor finish is applied after completion; once again, to protect the surface from damage. In a home, damage to concrete usually occurs from soda spills, food spills, and common household cleaner usage. Any of these materials may contain acids or other incompatible chemicals. If the protective coating is compromised, even if from simply dragging furniture and causing scratches, it is best to recoat those wear areas. An intact clear coat virtually insures household chemical mistakes cannot change the stained or dyed surface.


Stamped concrete is nothing more than pretty patterns etched, ground, or pressed into the surface to simulate tiles and stones. All types of coatings, dyes, and stains may be applied to the stamped surface. Treat these floors according to the coating type.

Next, assessing (A) the extent of the job will narrow down the amount of material costs and labor involved. It may even become evident that your company is not equipped to handle it. There is no shame in walking away in difference to a more experienced, better equipped concrete cleaning crew. It comes down to dollars and cents (or sense), as a mistake can cost megabucks to fix.

The biggest part of assessing the job is figuring the amount of labor required. This depends on your crew, your machine capabilities, and quality of chemicals used. Since we covered this thoroughly in Part One, let’s just add an assessment checklist:

  1. Take exact measurements of the floor space and calculate the total square footage (length x width).
  2. Decide on the types of cleaning equipment required based on square footage.
  3. Pick the cleaning crew based on capabilities compared to job size.
  4. Calculate the amount of labor time from beginning to completion based on crew speeds from past jobs using the equipment needed for the job.
  5. Figure the trip costs including loading, setup, takedown, travel, and fuel.
  6. Estimate the cleaning chemical requirements.
  7. Don’t forget about the sundries like replacement mop heads, scraper blades, gum removers, rags, absorbents, etc.
  8. Add about 5% to overall total to cover unexpected needs.
  9. Add about 5% more to cover equipment wear. Rotary grit brushes deteriorate through usage and are expensive to replace.

There is a difference between cleaning, refinishing, or resurfacing concrete. Resurfacing is not within the scope of what we are doing here. Cleaning and refinishing is what a cleaning company does. Unless it is your intention to become a slab resurfacing specialist, leave that to the specialists. Therefore, assess the cost of the cleaning and refinishing (if needed) only.

Contemplation (C) means to weigh the pros, cons, and rewards of taking on a slab job. Make a thorough list of materials required to complete the task, from floor machines to labor costs. Think about it – hard. Punch holes in it. Question the capabilities of your company. Suspect that you may have missed something and snoop for it. Mistakes are costly. Don’t even attempt a slab job unless you are totally confident that you have identified all the variables that may affect your profits. Oooopsies mean the difference between making money and breaking contractors.

Once all the costs are established, it is time to make a quotation (Q) – not estimation – to the customer. This usually comes in the form of a short contract for services that the customer must sign. NEVER take on slab work, or any other indoor cleaning project, without a written agreement stating exactly what work will be performed and at exactly what cost. Most cleaning companies make the mistake of giving an estimate rather than providing a fixed price based on differentiation, assessment, and contemplation. This leaves the idea in a homeowner’s head that maybe the cleaning company doesn’t actually know how to handle the job or at best, that there will be hidden costs to come around and slap them in the pocketbook. By giving an exact price in writing, several things will occur:

  1. The customer knows exactly where he or she stands on money owed.
  2. You know exactly how much profit to expect from the job.
  3. Both parties can move forward with confidence and understanding.
  4. If mistakes are made, at least they are honest ones, easier to forgive, and not due to a lack of differentiation, assessment, or contemplation.
  5. Since the contractor is ultimately responsible for everything that happens on the job, eliminate many issues by quoting properly.

Quotation (Q), therefore, is a matter of exactness, accuracy, care, meticulousness, correctness, fastidiousness. If a cleaning contractor operates under these auspices at all times, it is more likely that the moving facets of the job will fall properly into place. This is mutually beneficial to all parties – wouldn’t you agree?

That’s where acceptance (A) of the job comes in. Both parties – the homeowner and the contractor – must be in total agreement and understanding of every aspect of the proposed work. This reduces risks involved with working inside a home. What are the risks? Let’s list a few:

  • Water travels easily and sometimes goes where it shouldn’t.
  • Cleaning chemicals can cause damage to incompatible materials even though it doesn’t seem that they could.
  • Accidental damage can occur to furniture or other objects of value simply because cleaning equipment can be unwieldy in smaller spaces.
  • Like raccoons, sometimes employees see shiny baubles and just have to carry them off. Even if your employees have exemplary records, homeowners are very leery of unfamiliar folks having access to their stuff. Unwarranted accusations do occur. Bonded insurance is a must even if you work with your own family!
  • Homeowners are notorious for stiffing contractors if anything about the job becomes suspect. Get money up front to cover the costs before work begins. Fifty percent to start and fifty percent at the end is a generally reliable method. Most home cleaning jobs fall into the category of “petty” costs in small claims courts. Don’t go there. Use DACQAC instead. It’s cheaper.

Acceptance of the proposed cleaning job should be in writing. Although hand-shake deals are the way many contractors prefer to work, when it comes to the inside of a home (the castle, you know) forget it. Shake if you wish, but sign on the dotted line every time.

Now comes the final part: Completion (C). Completion does not mean hauling all the equipment back to the truck and heading out, although that’s part of it. No, there’s much more. Completing a job means that both parties are satisfied that the work was performed in the manner expected with the desired results achieved. Who should be the most concerned about how the job turned out? The homeowner? Not on your life! YOU, the contractor, the hired help, the promisor of great things to come, YOU are the ultimate judge on whether the job was completed to the satisfaction of all involved. There is an easy way to determine if the job has been completed properly though. Simply imagine yourself in the shoes of your client, the homeowner. Scrutinize the “completed” job as if even a hair found in the new acrylic floor coating were an affront to society. Dissect the entire performance from the first act of opening the door to turning off the light as you leave. Everything should be perfect, like a flawless diamond. Not a spec, not a scratch, not a single issue should be left unresolved. The homeowner should expect completion, but you should expect perfection. Never walk away from a job unless the customer is ecstatic with your work. This is Completion (C).

Now we’ve discussed the variables associated with DACQAC. But, are they truly variables? Perhaps, but I prefer to make them known factors by gaining knowledge and expertise. In reality, DACQAC is just another method of describing sound business practices. If we eliminate variables by making the unknown known, we can turn our mediocre companies into cleaning powerhouses. Unfortunately, most contractors fall short somewhere along the line. What separates the followers of DACQAC from the fallen is the experience of increased profits and success. “Hey man, your crew did a great job! The quote was dead on, the job was completed on time, and they didn’t make a mess, but got the place fixed up real nice! I’m gonna tell everyone I know!” Versions of the same comment will be commonplace, word will spread, prestige will rise, and services will be sought. In this line of business, word of mouth determines the success and failure. Make those words positive to turn your company into a lean, mean, cleanup success by using DACQAC as your modus operandi on every job!