Decorative Concrete Institute

Bob Harris

Consulting • Education • Installation • Training


Specialty techniques to take your stain work over the top

By Bob Harris

Basic one-coat stain applications with sealer and multicoat stain applications with decorative sawcuts form the largest percentage of chemical staining projects. However, a growing number of clients opt for something more when they see the design possibilities with various specialty techniques.

     With some imagination and skill, concrete artisans can broaden their horizons and take their work to the next level. Here are some of the techniques used to create one-of-a-kind concrete flooring.
     Concrete dyes - When concrete dyes are combined with chemical staining, there are no limitations from a predetermined color palette or color values. Dyes can produce bright, vibrant colors such as yellows and blues, and applicators have the ability to mix their own custom colors. Dyes can also soften areas where the chemical stain has produced an overly bright tone. Or they can enhance stain colors in areas of the slab where the stain is not reacting with the concrete.
     Decorative sandblasting - Intriguing effects are possible by sandblasting after staining, particularly when decorative stencils are used. The stencils are applied to the concrete surface before
sandblasting, so only the areas not covered are revealed. After the stencils are removed, the protected areas can be stained or dyed a contrasting color.
     Some manufacturers sell decorative stencils that are sandblast resistant and adhesive backed. Different degrees of tack on the back are available, so choose carefully. A high-tack backing could lift the sealer from the substrate or, in warm conditions, transfer mastic to the surface, which could be difficult to remove later. Conversely, a light-tack adhesive in cool conditions may not adhere aggressively enough. For this reason, most manufacturers recommend a coat of sealer prior to sandblasting to improve adhesion.
     Faux finishes - The same techniques and tools that have been used for years to faux finish walls can also be used on concrete flooring. Application tools include rags, torn paper, plastic and sea sponges to name a few.

     Applying a resist - A resist is anything that impedes the stain from penetrating into the surface of the concrete substrate. Sealer is often used as a resist, especially on projects with intricate sawcut patterns. Once the appropriate amount of sealer has been put down and has had suffici ent dry time, it forms a barrier that blocks the stain or other liquids from penetrating the concrete surface.
     With some creativity and experience using sealer as a resist, you can stretch your imagination. For example, incorporate "veins" into floor designs by applying sealer with an eyedropper or artist's brush prior to staining. Other application tools include crumpled rags, sea sponges and goose feathers. Keep in mind that not all sealers are equal, and a test panel should be conducted to check the suitability of the resist.
     Another way to resist the stain from penetrating designated areas is with masking plastic. However, this method is generally not practical for masking off detailed sawcut patterns.
     In addition to being used as a resist, sealers can add the final touch to a stained concrete project by enhancing the colors you have worked so hard to achieve. You can also choose from various degrees of sheen, ranging from matte to high-gloss.
     Gelled-acid etching - There are gels that can be used with decorative stencils in a manner similar to decorative sandblasting. These gels contain acid, which is responsible for its etching ability, but the acid is suspended in a gel solution so its interaction with the concrete is limited to the surface. Because of the product's gelatinous grip, it stays on the stencil and won't bleed underneath it, etching only the exposed areas to produce a very precisely etched pattern. These products also will not compromise the pH of the concrete, and it will not contaminate the sewage system after it is flushed.
     Engraving - High-performance engraving tools can cut intricate or one-of-a-kind designs into concrete. An assortment of engraving tools guided by templates are available in thousands of patterns and designs, including letters, logos, borders and custom graphics. The tools can also be used freehand.
     Small wheel-mounted decorative concrete engraving saws can be used to do engraving work in small or restricted areas. When equipped with an optional center pivot, they can also cut perfect circles.
     Fertilizer - The iron and nitrogen in fertilizers, such as Miracle Grow, dissolve and leave unique etchings on the concrete floor. One of the more popular techniques is to use fertilizer pellets. Usually the pellets are applied
to the concrete surface prior to staining. However, some artisans will first apply a base color of stain and then apply the fertilizer pellets followed by a second color of stain to achieve different effects.
      Sawdust and kitty litter - When applied to the concrete surface during staining they will absorb the stain and leave an outline on the concrete floor. As with fertilizer pellets, sawdust or kitty litter can be applied at different phases of the project to create different effects. Sampling is essential to achieving the exact look you are after.
     Other common absorbent materials used to create special effects include corn flakes and metal shavings. The possibilities are unlimited when you use some of these materials combined with staining.
     Torn paper and rags - Any item with a ragged edge can be used to transfer the look of a vein or cracked edge onto the floor. Stain or dye can be sprayed across the edge of torn paper to achieve this effect. Or rags (torn into strips) can be applied to the concrete survace and then stained to create the look of a crack.
     Air - Accents can be created by "blowing" the stain across the surface, using compressed air force through a fine tip. For example, by applying stain with an eyedropper into the channel of a decorative sawcut, and then using the air tool to blow the stain out, you can achieve the delicate look of vines or ferns. Be aware that while using air, some of the stain can become airborne. It is essential to wear protective gear and safety glasses or goggles when using this technique.
     If you choose to add some pizzazz to your stain work using one or more of the techniques described, you must practice the applications on sample boards to perfect the process before proceeding to the big leagues on your client's floor. Hopefully a few of these ideas can help take your stain work over the top by separating your floors from the boring one-color application.

     Bob Harris is the founder and president of the Decorative Concrete Institute in Douglasville, Gal, which provides hands-on training seminars in architectural concrete. He has pesonally placed or supervised the placement of more than 3 million sq. ft. of decorative concrete and has authored two best-selling books, Bob Harris' Guide to Stained Concrete Interior Floors and Bob Harris' Guide to Stamped Concrete.