Whether it’s the stucco on your home, terracotta roof tiles or your residential driveway, color can be the most immediately noticeable and the least expensive element during the building process.
Having said that, some contractors have a hard time developing the confidence to use it properly, especially when choosing a variation of color combinations to complement surrounding structures. If one chooses color combinations from the existing structure and incorporates them into the stamp work, the project will blend harmoniously.
An example of this would be to start with your base color selection. This color may be a beige or buff color which matches your siding or stucco color. Choosing your next accent color may come from the trim around your windows or from the roof tiles.
Having an understanding of color theory is a valuable tool to include in your toolbox, but knowing which products to use to achieve these color combinations can be an art of its own. Let’s review the most commonly used methods of coloring your stamp work.
Integral color is easy to use because it is typically mixed into the concrete at the batch plant to achieve uniform, homogeneous color. Integral colors are available in powdered, granular or liquid forms, and sometimes contain admixtures, referred to as a colored admixture.
A big advantage of using integral color is labor savings. You don’t need to float the color into the surface during finishing, as you do with shake--on hardeners. Another plus is that the color is permanent because it extends throughout the entire matrix of the concrete. So even if the slab surface is accidentally chipped, scratched or abraded, the integral color will remain, unlike with surface--applied treatments.
A disadvantage with integral color is that the hues are more subtle and less vibrant than what you can achieve with color hardeners. You’re generally limited to soft earth tones, such as muted browns, reds and tans. Although you can obtain pastel hues with integral color, such as blues or greens, doing so is usually cost prohibitive. To achieve good color intensity with these lighter hues, you would need to use a white cement and a high dosage of pigment, resulting in a significant increase in concrete costs. For that reason, stamping contractors often use integral colors in conjunction with surface--applied treatments — such as color hardeners and chemical stains — to create layers of color.
Dry--shake color hardeners
For brighter colors, dry--shake color hardeners give better results and come in an unlimited range of color options. The hardeners are broadcast onto the fresh concrete and then floated into the surface before imprinting. To work properly, the color hardener must “wet out,” or absorb some moisture from the slab. Because these products contain fine aggregate and cement, as well as other ingredients, they actually densify the surface and make it less permeable, so some surface strengthening can be expected.
While dry--shake hardeners are more labor--intensive to use than integral coloring, they are comparable in price overall with integral color because you’re not coloring the whole matrix of the concrete. Hardener is applied only in the quantity needed to color the top 1/8 to 3/16 in. of the slab. Most seasoned stamp professionals prefer the color hardener option because of the range of color that can be obtained, but also they claim you can achieve a cleaner imprint since you’re imprinting a layer of paste as opposed to the course aggregate typically found in ready--mix concrete.
Pigmented powdered or liquid release agents serve dual purposes: They act as bond breakers to prevent the stamping mats or skins from sticking to the concrete and disturbing the imprint texture, and they impart subtle color to the concrete that enhances the intregal or dry--shake color, resulting in an antiquing effect.