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Acid-Stained Concrete: Why Use A Floor Finish?
This acid-stained grocery store floor in the Detroit metro area has been well maintained. Photo courtesy of: Qualified Construction Corp.
Every successful acid-stained floor project requires a long
term, protective, clear coating system. Choosing and applying the proper
system, however, can be a daunting task to someone without a background in
floor coatings or chemistry. Select the right system, and your floor will be
easy to maintain and last indefinitely. Pick the wrong system, and problems
will arise almost immediately and compound themselves over time. Most people with an appreciation for acid-stained concrete flooring understand that it needs to be sealed. What is less well understood is the necessity for using a floor
finish, or “polish”, on top of that sealer. Because of this common oversight by contractors and project owners alike, there are many unsightly,
damaged acid-stained concrete floors on display today, in restaurants and
other commercial locations throughout major metropolitan areas, that serve as
a visible deterrent to the continued growth in use of this flooring
"iShine", a high solids floor polish from Spartan Chemical that imparts maximum gloss, optical clarity, and durability to a stained concrete floor.
There are numerous, worthwhile and essential benefits from using a floor polish that cannot be derived through a concrete sealer alone. A good floor polish provides: 1) increased slip resistance; 2) increased water resistance; 3) good scuff resistance against black marking from shoes, furniture legs, and wheeled traffic; 4) improved "lubricity", so that stationary objects don’t stick to the floor; 5) a softer luster, or "feel", to the floor; 6) good absorbency and deflection, preventing the sealer from being chipped; 7) much shorter dry times than sealers; 8) easy "buffability" to restore gloss; and 9) ease in stripping and replacing. In short, floor polish provides a very user friendly interface with the concrete sealer that can be easily repaired and maintained. This interface is frequently referred to by the industry, as a “sacrificial layer”.
The clear sealer is just as important to acid stained concrete flooring
,but is meant to be
more of a “permanent”, protective layer. Consequently, its purposes are slightly different and more
basic: 1) to enhance or deepen the color or
tone of the stain; and 2) to provide long term
protection for the design and floor color from harsh environmental forces, such as accumulated moisture, chemical spills,
heavy abrasion, and repeat wear patterns. Unlike floor polishes, most sealers are very hard and well-adhered. They are not meant ever to be removed. Because sealers scratch and chip relatively easily, this means that they are difficult and time-consuming to repair. Using a floor polish helps to ensure that no damage is
ever done to the sealer, and that ultimately no expensive fixes to the floor are ever required.
Carnauba, a hard, natural wax used alone on floors in the early 1900's, it is now added to floor polishes to provide buffability and a deep, wet look gloss.
The basic difference between a sealer and floor polish is in their composition. Sealers are entirely composed of a resin or polymer, such as an acrylic, epoxy, or urethane. Floor polishes are primarily (about 80%) based on a resin or polymer; but the difference lies in the addition of a natural or synthetic wax (approximately 10-15%). This addition of wax is responsible for many of the floor polish benefits outlined above. This wax also makes the formulation of floor polish much more complex, and therefore requires other ingredients: modifiers (5%), such as "dibasic esters", to make the polymer and wax compatible. Because of this complex formulation, applying floor polishes in an appropriate manner becomes critical. Specifically, floor polishes almost always need to be applied to a clean, dry, pH neutral, non-porous (sealed) surface in extremely thin coats, and within a certain range of temperature and relative humidity. If applied incorrectly, a floor polish may remain tacky, haze over to a "white" appearance, streak, or turn to powder.
Because floor polishes are more complex, manufacturers
also generally carry numerous formulations (see
that vary in solids content, hardness, type and amount of polymers (acrylic
& urethane) and waxes
(natural & synthetic) used, chemical resistance, and depth and clarity of shine. Therefore, it is important to pick the right
polish for the particular building environment, and the anticipated maintenance
program. For example, not all floor polishes are "buffable". As a
result, buffing a polish that is not meant to be buffed, may result in swirls
and scratches, while neglecting to buff a finish that is meant to be buffed, may
result in quick yellowing and discoloration, since these polishes are softer
and accumulate dirt more easily.
Maintenance programs for marble floors usually include a "buffable" floor polish and a high-speed "burnisher" to preserve a high degree of gloss.
One great benefit of floor polish that few people are aware of is
its ability to
adjust the gloss of sealed, acid-stained concrete. Most concrete sealers are relatively glossy. This look is generally desired in commercial
and residential environments, but the high light refraction associated with
gloss sealers can be bothersome to people in medical and institutional surroundings,
and simply unappealing to owners interested in a "warehouse" lool floor. Using two or more coats of a “matte”, or
even “satin”, floor polish on top of a concrete floor sealer will tone down its gloss considerably. Floor polishes are
“matted” by using a particulate additive, (e.g., silicon), hard wax (e.g., polypropylene), dull resin (e.g, polyvinyl acetate), or liquid compounds of these materials (e.g., silica gelled waxes). Also, because of the complex formulations involved, even floor polishes that have not been dulled in any way
usually still vary considerably in gloss from one brand to another.
This acid-stained entertainment room floor is a good example of the dull or "matte" sheen that can be achieved with a matte floor polish or low gloss sealer. Photo courtesy of: Alpine Concrete .
Sealers can also be used to dull a stained concrete floor’s gloss. But there are several common problems with this approach. Most sealers are flattened by using fine particles, such as silicon, talc, chalk, metal soaps, or polymer beads. These particles tend to coagulate and/or settle out of suspension in a sealer during application. The result is often a "streaky", or "seedy", look to the floor with uneven, isolated patches of gloss. This can also be a problem with floor finishes, but the use of a wax in the formulation aids in dispersing the flattening particles, and helps suspend them near the surface. Another problem with the use of flattening particles in sealers is that they tend to interfere with strength and durability, making a sealer more brittle. This can lead to flaking and delamination of the sealer, a common problem with stained concrete floors. "Brittleness" is not a problem with floor polishes because the wax component usually makes up for any loss in plasticity due to particulate additives. Finally, sealers can be dulled by using certain resins, such as treated acrylics or polyvinyl acetates, or by including chemical (usually acidic) modifiers. These sealers, while a little more durable than those flattened with particles, are still less durable than typical gloss sealers, and usually can only be dulled slightly, to a “satin” rather than full “matte” appearance.
Diversey''s "Carefree Matte" can be used with most concrete sealers. The company makes its own line of commercial cleaning and hygiene products..
With the growing popularity of acid-stained concrete, home and business owners are beginning to fine tune their preferences with new flooring projects, not only in terms of design, but gloss as well. Accordingly, Premier Veneers has tested, and experimented with, several matte floor finish products over the past year. We favor Carefree Matte, by Diversey. It can be found online, or at local janitorial supply houses. XL Matte Floor Finish, from XL North, is also available online. Both of these floor finishes dull a glossy stained concrete floor very nicely, don’t streak, and are easy to apply. We routinely use and recommend Spartan polishes, where gloss finishes are suitable, but they no longer carry a matte floor finish. We have evaluated the matte polishes from several other companies as well, such as Johnson, EcoLab, and Glaze 'N Seal, and these products fall into a third, fourth, and fifth tier because they use particulate additives rather than dibasic esters, and these particulate additives vary in size from large to small, which is the least effective size for modifying gloss.
In conclusion, a good floor polish is always necessary on top of a properly sealed acid-stained concrete floor. It will help preserve the floor’s initial appearance and condition indefinitely. Furthermore, because floor polishes are so inexpensive (about $15-$18 per gallon), and easy to apply, there is really no good reason not to use one. Given their complex formulations, however, it is imperative always to test polish on a small area of sealer, for compatibility, before doing an entire floor, and then to follow the manufacturer’s application instructions ,as closely as possible.