Art Concrete How-to
5: Color and Dye for Concrete
THIS PAGE is one of several explaining techniques about how to use concrete in small-scale art projects.
| Book: Concrete Handbook for Artists: Technical Notes for Small-scale Objects. More information? |
Concrete can by coloured or dyed with a limited palette of several colors. Because the portland cement is caustic, some pigments that work well in paint media are attacked by the causticity, resulting in colour break-down over time. To be certain, you must use pigments that have been proven to last when mixed with concrete.
The most typical concrete colours are earthy: brick or rust red, buff or yellow ochre, brown, charcoal (close to black). Green is less common and more expensive. Blue is even more expensive. (How often have you seen blue concrete?) Most colours seem to be derived from iron oxide or cobalt. There are lots of color charts to view the range of colors available.
The colours typically come in a powder form, or mixed with water as a paste. Getting a deep rich colour can be a problem as most of the pigments have a maximum percentage (usually 10%) that can be used before they weaken the mix, so you can be left with a weak concrete with a good colour, or a strong concrete with a pastel shade. Often the main body of concrete is mixed without the dye, and then a mix of cement and pigment used as a top coat. This gives you the strength, with a deeper colour on the surface.
Acid stains work by painting the acid stain on the surface. The acid creates porosity and the stain penetrates. You can also stain the surface of concrete using water-based, or acrylic, opaque stains. These stains are made to be used with outdoor wood, so I am not sure about long-term colour-fastness when used on the surface of concrete exposed to the weather. Apply with a stiff brush and wipe off immediately with a slightly damp cloth. This leaves the colours imbedded in the texture of the concrete.
Concrete tiles, stained with acrylic outdoor stains.
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Last update: 2016.