Concrete Staining

     The main reason concrete floors are stained is that paint, even special concrete paint, does not adhere well or last.  Concrete stains are also chosen instead of colored epoxy coatings, for example, because its translucency helps make concrete look like something stylish and expensive, such as marble, granite, travertine, flagstone, and other forms of natural stone, rather than something merely utilitarian and functional.  Decorative concrete scoring may then be used to provide patterning effects to this marble or "natural stone" appearance.  Here are some of the most popular Acid Stained Concrete Scoring Patterns.

     There are a variety of concrete staining products.  Acid stain is probably the most popular, but for
wider color range or variation, and greater control over detail, tints, concrete dyes, and acrylic concrete stains (water-based and solvent-based) are also used.  For an illustration of acid stain colors, see:  Decosup Acid Stain; Scofield Acid Stain; and Artcrete Acid Stain.  To view some of the brighter colors attainable with tints, concrete dyes and acrylic concrete stains, please refer to:  Scofield Water-Based Concrete Stain.  We use the full range of concrete coloring options.  We have done extensive research, testing, and experimentation and have found that these are the best concrete staining products on the market today.

Many people think concrete staining is a do-it-yourself project, and it can be.  But to achieve the faux stone effects that make people think they're seeing something they're not, and to avoid the many pitfalls that can quickly ruin a stained concrete flooring project, takes skill and experience.  That is why our clientele chooses us:  to bring a realistic and fluid feel to their concrete floor that augments the elegant look they've already established through architecture, furnishings, lighting, woodwork, and paint or wall coverings.

A misnomer about acid stains is that they are hazardous to work with, require special means of disposal, and are not a "green" product.  It is true caution must be taken to prevent skin contact and breathing of fumes during application, but when following proper procedure there is no great risk to the applicator, and practically none at all to others nearby.  Acid stains are 95% water-based and generally contain only 5% or less muriatic acid.  This acid is neutralized upon contact or reaction with the concrete.  And the metallic compounds that most acid stains use for coloring are commonly found in soil and fertilizer:  iron, copper, and manganese.  Unlike many other building products and materials, acid stains leave no lingering harmful effects after application and installation.

Concrete Overlays

Sometimes, because of age, abuse, cracking, or previous floor treatments, an existing concrete slab cannot be effectively stained.  In such instances, thin polymer-modified cement overlays can be installed, quickly and inexpensively, to provide a new concrete floor surface to work with.  At depths as shallow as 1/8", these "concrete veneers" are durable and permanent, and allow for great creativity in coloring and patterning.

	Decorative concrete overlays normally come in white and gray, and they may be stained as they are, or they may be integrally colored and then stained, to provide a unique, customized, color pattern that cannot be achieved with concrete stain alone.  Decorative concrete overlays may also be integrally colored and then (rather than staining) topped with another thin, colored cement overlay that allows the first overlay to show through slightly.  This provides a more subdued color effect than staining.  Finally, concrete overlays may stenciled or stamped at the time of placement to impart patterning and texture along with the color.

Concrete overlays may be applied in any one of several different manners.  After preparing the concrete slab through acid etching, grinding, or shot blasting, some cement overlays are troweled over the concrete slab.  Other overlay products, called self-leveling overlays, are poured onto the concrete floor and then spread evenly with a gauge rake and smoother.  Finally, some cement overlays may be applied with a roller or sprayed.  The type of overlay product used typically depends on the durability required by the project environment, and the decorative look trying to be achieved.  For example, trowel-down overlays generally exhibit greater color mottling or "antiquing" from concrete stain than do self-leveling overlays.  Most overlay products, regardless of application method, require sanding with a rotary floor machine, after installation to optimize the surface for accepting color from the concrete staining product being used.

Concrete Engraving      Using an air compressor, pneumatic cutting tools, and a heavy-duty plastic template, images and designs, such as patterned borders and company logos, can be precisely and efficiently engraved into concrete.  Concrete engraving becomes a permanent and elegant part of the concrete surface, and at only 1/16" depth, does not present a trip hazard.  Images and designs may be chosen from a preset catalog or converted from any electronic image file.  In the photo below, the sketch of a design on a jewelry case was reproduced on the main floor of an Irish pub in Farmington, Michigan.  You can read more about the concrete engraving process and see a catalog of available templates at:  Engrave-A-Crete.

Decorative Scoring

If you have a large, open floor that isn't obscured by a lot of furniture, scoring lines and simple geometric patterns into acid stained concrete is a great way to break up the monotony of a single color and draw more attention to your floor.  Concrete scoring lines are generally made with a guided angle grinder, fitted with a diamond blade and a dust-free attachment, and are usually 1/8"-1/4" wide and deep, although you may specify exact dimensions if you wish.  The lines may be filled with a colored grout to accent the colors in the floor, or left as they are, for a subtle appeal.

Straight wall borders and large square tiles are probably the most popular decorative scoring patterns, while arcs, circles, and diamonds may be chosen for a more contemporary or artistic look.  Notice the large-diameter circular border in the photo above right; and the large square tile pattern in the photo at direct right.  Finally, for added accenting, concrete scoring lines may be used to separate stain colors.  Here are some of the most popular Acid Stained Concrete Scoring Patterns.

Stenciled Overlays	Stenciling is used in decorative concrete to add patterning effects that are too complex or detailed to be reproduced on concrete

through the scoring of lines.  Concrete stenciling can be done in a variety of methods.  First, a thin cement overlay may be sprayed or trowelled over a stencil, removing the stencil once the overlay has hardened.  This is the method used in the photo to the left.  It is best for repeating patterns like brick, cobblestone, and slate, and may be used over an entire area or just as a border.  You can see some of the patterns available for stenciled concrete overlays from:  Artcrete Concrete Stencils.      Stenciling can also be done by etching the pattern into concrete or a cement overlay using plain or colored, gelled muriatic acid.  This method is best for intricate patterns that require great attention to detail, such as stylish borders and complex custom images.  These patterns become a permanent part of the concrete but go no deeper than 1/32".  You can see samples and read more about this process at:  Modello Concrete .  Finally, concrete stenciling can also be accomplished through the engraving process (described above), where greater physical depth is desired than can be achieved through concrete etching.  See an example of an engraved stencil here.

Concrete Surface Preparation

Concrete surface preparation is the most important part of any decorative concrete flooring project.  For the project to hold up over time, you must begin with a surface that is clean, dry, and sound.  Unless you are starting with a brand new concrete slab, this often means beginning by removing tile adhesive, carpet glue, or paint, and sometimes a combination of these three residues.         Clean:  Yellow adhesive, shown in the first photo at right, is water-based and is common today with vinyl tile and carpet.  Black adhesive, shown in photo two, is solvent-based and found under tile in older homes.  There are environmentally safe products on the market that are effective in stripping both from concrete floors; the problem is that tile adhesives often leave indelible stain patterns behind, as seen with the tile pattern in photo three.  The more predictable and efficient method of removing adhesive and glue is concrete grinding, shown in photo four.  You can see how effective it is in "cleaning" the concrete.  While chemical stripping and grinding are sufficient in most situations, even more aggressive methods, such as shot blasting and scarifying, are sometimes required, for example, in removing the thin-set mortar beneath ceramic and porcelain tile.  The down side of these more aggressive methods, however, is that a cement overlay is usually then required to cover the gouging, pitting, or other resulting damage to the surface of the concrete.         Chemical strippers are most effective in removing thin layers of paint, as well as excessively sticky adhesives that would clog grinders.  Paint overspray, drywall mud, and other stains or markings can usually be removed with a rotary floor scrubber, detergent, and warm water, or a grinder fitted with a "ZEC wheel", which is less abrasive than the diamond cups that are normally used in grinding.         Dry:  Once the surface is clean, it should be tested for moisture content and moisture transmission.  Excess water in concrete can

cause problems with stain color, and the adhesion and clarity of concrete sealers.  Because there are a variety of testing methods for moisture in concrete, and some require special equipment, this is best left to a contractor or professional.  If moisture is determined to be a problem, and does not have an identifiable cause that may be fixed, dehumidification equipment often helps aid in drying the concrete to acceptable levels.  New concrete requires at least 28 days to cure.      Sound:  Lastly, concrete surface preparation may require repairing cracks and patching holes.  These tasks can be done effectively with epoxy slurries or cement mortars.  Such concrete repairs, however, usually do not blend in color with the rest of the floor, and even if they do, they usually do not accept concrete stain the same way.  If the repairs are small and few in number, artists' tints and faux finishing techniques may be used to disguise them.  If the concrete repairs are larger in size and greater in number, however, a cement overlay may be required to remove all signs of them.   Once the concrete is clean, dry, and sound, you have the basis for a successful decorative concrete project that will last for years to come.