Coloring Techniques for Concrete Countertops
There are three common methods for coloring concrete. One way is by using integral pigments. Another way is to acid stain the concrete, and the third way is to use a dye.
In actuality there are a couple of other ways which change the appearance of the concrete, but they are not methods that most people use or consider when they want to change the color of the concrete itself. Large quantities of decorative aggregates, either colored stones or crushed glass, will alter the appearance of the concrete and provide an overall color change; terrazzo is an example of this. Generally decorative aggregates are most often used as an accent rather than the prime method for coloration.
And even further outside the general notion of coloring concrete is to tint or pigment the sealer that is applied to the concrete, or to use a pigmented wash (sometimes called a stain, which should not to be confused with acid staining). This technically is no longer colored concrete, rather it’s more like paint applied to ordinary concrete.
This article deals with the three most common methods for coloring concrete: integral pigments, acid stains and dyes.
Integral pigments are a very common method for coloring concrete. Pigments are very finely ground particles of inert colored material that are mixed into the concrete (usually during mixing, or sometimes during trowelling).
Integral pigments can be powders or liquids. They can be natural minerals, manufactured metal oxides or synthetic materials. Integral pigments offer the widest range of color options that span the entire spectrum. Pigments can be pure white, deep black, red, bright yellow, blue, purple, green, brown, orange, etc. Pigments can be blended into a nearly infinite range of shades and colors, offering virtually the same color range as the paint industry.
Integral pigments provide versatility and dependability. The strength of integral pigments is their huge color range and their consistency. Pigments are the most consistent and highly controlled ingredient in concrete. As long as careful batching, mixing and curing procedures are followed (paying special attention to controlling the mix water), the resulting color consistency can be very high. With integral pigments, it’s easy to achieve the same color and the same look over and over again, as long as the your concrete countertop craftsman is meticulous.
Integral pigments get mixed into the concrete, so the entire body of the concrete is colored (although there are methods that don’t require coloring all of the concrete in a slab). This means that significant quantities of pigment are required, and this leads to perhaps integral pigments’ downside. Some pigments are more expensive and harder to find. Pigment prices can range from $2/lb to over $60/lb, and while many of the standard iron oxide colors are widely available from a number of manufacturers, some of the more exotic colors are available from only a few small distributors. A concrete countertop craftman may charge more for concrete colored with some of the more exotic colors.
Here are a few pictures of concrete colors achieved with integral pigments.
Integral colors can be subtle:
Soft sage green countertop
Penny colored countertop with rustic edge.
Piece of turquiose embedded in edge of bright red countertop
Aqua blue oyster bar with blue glass
Or combined with other effects to create different looks. The following two countertops use a bit of black pigment to create a dark gray concrete, but then use stone and glass in different ways to create very different looks.
Traditional look achieved with gray concrete and cream/tan stones and traditional edge.
Contemporary look achieved with gray concrete and black grout and clear glass.
Acid stains are another very common and effective way to color concrete. Like integral pigments, acid stains are permanent and most can be used inside and outside. Unlike integral pigments, acid stains are applied to the concrete only after it has cured. Integral pigments are used primarily because they are uniform and predictable. Acid stains are mostly used for exactly the opposite reasons.
Acid stains are chemical solutions that react with the concrete to form color. Each different acid stain contains a particular metallic salt that reacts with the calcium hydroxide in concrete; the acid makes the reaction possible.
Acid stains are reactive; for this reason, they are somewhat unpredictable, or as some people prefer to say, more spontaneous. While the color of the acid stain won’t vary much from what’s expected, the shade and intensity will. The intensity of the color is dependent on both the concrete and the acid stain. Since the acid stain reacts with the concrete, the age, ingredients, texture, curing method and finishing method (honed versus trowelled) all have a strong influence on the final result. And the stronger the acid stain solution (the less dilute it is) and the longer it is allowed to react with the concrete, the more intense the color will be. So the end result is a beautiful mottling of shades and intensities, where the exact end result cannot be predicted.
Acid stains come in a limited (but popular) range of colors. Browns, rusty reds, orangey-browns, bluish-greens and yellow-greens typify the colors commonly available. While the colors are generally the same or similar from manufacture to manufacturer, the strength of the acid may vary, and this influences the color. Acid stains are slightly translucent. The finished color is dependent on both the color of the acid stain and the color of the underlying concrete.
Acid stains form the color on the surface of the concrete. Smooth, dense, high quality concrete, which is very typical in concrete countertops, is not very porous. Acid stain color does not penetrate very far into the concrete. Typically it is only a few thousandths of an inch deep. Because of this the color can be worn off from prolonged abrasion, so some sort of sealer generally applied over the stain to protect it. This is more often a concern with floors than with countertops.
It is possible to mix some acid stains together, and it is possible to apply one color over the top of another acid stain. And acid stains can be applied over integrally pigmented concrete. This is a good method for getting the best of both worlds: achieving a particular color and overall evenness of tone but capturing some of the unpredictable mottling too.
Since acid stains are applied to cured concrete before it is sealed, only a small amount is needed to color a large amount of concrete. Typically a gallon of acid stain costs about $50 to $70, but will color several hundred square feet of concrete. This makes them very economical.
However, the skill involved in applying acid stains and knowing what effects will be achieved does not come cheap. It requires a great deal of experience and attention to detail. A craftsman who has experience in acid stained concrete floors is often a good candidate to apply his or her skill to acid staining concrete countertops.
Acid staining is also a popular technique in conjunction with stencils. Stains can be applied before and/or after stenciling to achieve a variety of effects.
Brown over copper with Modello stencil
Traditional look achieved with amber acid stain and floral edge
The third method for coloring concrete is by using dyes. Dyes, like acid stains, are applied to cured concrete, and they can be applied over integrally pigmented and acid stained concrete. Unlike acid stains, dyes are not reactive. Dyes are ultra fine particles of color in some kind of liquid carrier, most often water or solvent, such as acetone.
The ultra fine particles “stain” the surface while the liquid carrier quickly evaporates, leaving very little or no residue. This quick evaporation (especially with the solvent based dyes) can be both a benefit and a drawback. Most often they are sprayed on, but they can be brushed, rolled or wiped on. Brushing, rolling or wiping a quickly evaporating dye will almost always lead to streaks or blotching, so spraying is generally used to ensure an even coloration.
Dyes can provide a wide range of colors, from duplicating the colors of acid stains to rivaling the colors of integral pigments. Rich, vibrant colors are possible with dyes, and because they can be diluted, mixed and layered, the color possibilities are nearly endless. Like acid stains, dyes are slightly translucent. The finished color is dependent on both the color of the acid stain and the color of the underlying concrete.
While dyes provide great versatility, especially when used as an accent or an easy means of coloring specific areas or designs in the concrete, dyes can be limited to where they can be used. Not all dyes are UV stable, and some must be used under sealers that block UV light. Water based dyes tend to be less UV stable and can bleed or smear if a water based sealer is applied over them. Solvent based dyes tend to be more UV stable (but always check with the manufacturer to find where and when to use them), and these too can bleed or smear if a solvent based sealer is applied to them. And like acid stains, dyes only color the surface of the concrete. Their beauty is only skin deep.
A significant advantage that dyes have over acid stains is that because dyes are not reactive, there is no residue to clean up after the dye is applied. This means that they can be sealed almost immediately after application (once the liquid carrier evaporates), making the project faster.
And finally, like acid stains, dyes can be very cost effective because a little goes a long way, but again the skill does not come cheap. Dyes are often used by highly skilled artists to create stunning works of art on concrete.
Several photos and more information about dyes are available at http://www.concretenetwork.com/concrete/concrete_dyes.
If you are a homeowner who wants a unique countertop, talk to your local craftsman about the types of coloring options he or she provides.
Whatever look you want to achieve, it is possible with the myriad coloring options for concrete countertops.