Mitigating the expense of diamond polishing
“Expensive” is a fun problem to solve. I take Ingvar Kamprad’s quote to heart and I go to work every day on the internal efficiencies of element7concrete. I look at the business as a vehicle, and like the clear engine cover on an exotic sports car bonnet i, I want the mechanisms of delivery to be worthy of complete transparency.
Mitigating a comparative lack of stain resistance
Regarding the technical weaknesses of polished concrete - the lesser resistance to staining, it’s important to first review our priorities and give some background info. Again, our ranked objectives start off as
- Will it work 100% of the time in the real world? (regardless of moisture passing through the concrete slab, efflorescence, etc.)
- Does it look great?
- Is it durable?
- Can we easily service it in 5, 10, 20, or 30 years?
Regarding the 1st, that is why we are not coating or sealing concrete as most slabs in our area eventually pass enough moisture to create a bond issue somewhere and / or efflorescence (white salt that migrates out of concrete).
Regarding our second objective, we have found some polished concrete guard products have color enhancers that make colored floors look categorically better.
Regarding durability and servicing the floor, a quick definition is in order for “polished concrete guard product” (PCGP). These are impregnating or thin-build sealers for polished concrete. They generally are to be burnished after installation with a diamond impregnated pad on a heavy (propane powered) burnisher (pictured below). Some of these materials form films (Scofield’s Guard-W, LYTHIC Protector, H&C’s Lithium Protective Finish, etc.), others impregnate the slab (CPS Stain Armor, GranQuarz 355E), and some do a bit of both (AmeriPolish SP and SR2). There is no 1 PCGP that we can say is categorically ideal, but the combination of a water-based latex acrylic on the first pass for or resistance to acids and a color enhancer, with a solvent-borne siloxane on the second coat for its resistance to oil-based stains seems to be ideal.
We use a densifier with a bit of siloxane in it that is engineered to bond well with a polished concrete guard product (PCGP) that has a water-based latex element for resistance to acids and a color enhancer.
A deeper look into the challenges of refinishing
Coatings and sealers make a lot of sense in places where everything could be moved out after a decade or two of use for repair. However, interior floors of homes do not fit in this category. Sealers on floors will get scratched, and applying more sealer to a scratched floor results in an unattractive texture. Stripping sealer requires grinding or harsh chemicals. There is a new generation of strippers that are supposedly soy or citrus based and therefore safer, but as an installer I can tell you these chemicals are NASTY. I’m not a real sensitive guy, but even with a Tyvek suit, gloves and a respirator I felt sick enough to not want any of my people to have to use these materials again. A little research into the SDSs for these materials show they still contain Dipropyleneglycol methyl ether, Petroleum naphtha, N-Methyl Pyrrolidone, and though they add citrus terpenes to make them smell natural, they are not good to be around! Installing something that will get scratched up and require these chemicals to remove seems frankly irresponsible to me.
A deeper look into this industry.
Most companies polishing concrete with fall into 2 categories: growing companies working to serve bigger and bigger commercial clients or boutique installers. David Stephenson writes “Over the last few years, there’s been a change. The medium-sized contractors seem to be disappearing rapidly. It seems the owners of these companies have made a conscious decision to either get smaller or larger. If they choose to get smaller, they focus on higher-end projects that carry maximum margin…On the flip side of the coin, many owners have decided their best path to success is to grow larger.”
So what? So the tools and materials made available either maximize the consistent service of nationwide accounts or the wowing of clients by boutique installers. The former is where the money is for the suppliers, and polishing is frankly boring for most boutique installers so they tend to focus on coatings, castings, and overlays. Neither of these directions add up to the most durable, efficiently installed floors possible. The consistency needed for nationwide accounts undermines the efficiency and durability because step 1 there means removing the trowel marks by cutting the cream of the concrete off. This is the hardest, most durable part of the concrete, and everybody knows it. But having a consistent look across all stores is of more value to that customer. The boutique installer is more focused on novel finishes than durability.
What seems to be lacking for everybody is objective standards for testing and clear data. Sellers of materials have pinned a lot of faith on chemical floor hardeners as they have the widest range of application methods. In 2014, George Garber referenced an interesting study in his articlee for Concrete Construction Magazine. It turns out Massud Sadegzadeh and Roger Kettle at Aston University in the U.K., compared 2 kinds of silicate floor hardeners over 30 years ago. Their work shows a 15-38% improvement in wear across slabs of varying quality for both. This concurs with the CPAA in 2009 on concurring that all floor-hardening materials, if applied to rejection, do the same thing. Again it was shown that the fundamentals of concrete placement (low water/cement, thorough consolidation, good finishing practices, proper curing, etc) are more important than brand of chemicals applied after the fact. The challenge with these findings is that they don’t help sell anything. What we have found as the solution is to cultivate good relationships with the best placement contractors and work with homebuilders to find enough in the budget to get a great slab of concrete to start with.
A backwards customer experience
Back to the moon question: we are still doing 100s floors every month, and I still run into customers every time I go to the grocery store. What we have found is that almost every client learns to love their floor over time. No matter how understanding they are, the initial installation leaves them wishing something was different. However, those become the beauty marks they learn to love. Additionally, we have found that “densifiers can take 2-6 weeks to attain full densification” Technical literature for PCGPs (polished concrete stain-guard products) all seem to say “gains its full stain repellency properties in 7 days.” Color can change over time, and perception of color will change almost every time. Concrete floors done in this way seem to please more over time than when new. Therefore, we believe this is the closest answer to “What is the best, most efficient thing to do for flooring?” Thank you for your interest in sustainable flooring. Please email me at email@example.com with further questions.