How Does Precast Get its Color?

I am often asked how the surface treatment of the precast panel will affect the color and what are our “standard” colors?  This is not as libertyelementary_finish01simple of an answer to give as one might think and the first step is to understand what makes up the color.

  • Cement—White or grey and /or mixed in a percentage, such as 50-50 or 75-25.
  • Pigments—Coloring agents used to dye the concrete.  The majority of precasters will use between 0-5%
  • Fine aggregate—There are a multitude of sands available from white to black and all colors between.
  • Course aggregate—There are a multitude of rocks available from white to black and all colors between.
  • As Cast Finish—This will have the color of the concrete or pigment.
  • Acid Etch Finish—This will slightly etch the surface of the concrete and will expose the color of the matrix with the color of the sand.
  • Sandblast Finish—A typical sandblast finish will roughen the surface enough to expose the color of the coarse aggregate rock.
  • Exposed Aggregate/Water Wash Finish—A chemical retarder is applied to the form before casting which allows the cement paste to be removed and exposes the natural stones used in the mix.

Just by using the above items, you can create thousands of combinations.  PCI.org has a color and texture guide available on their website with hundreds of examples of concrete mix designs.  I would recommend talking with your local precaster, as this is just meant as a guide, and it is best to find out what is locally available.

libertyelementary_waterwash-acid-etch-sandblastThis example is the same mix design with the three different surface treatments: Sandblast/Acid Etch/Water Wash

Steve Olson
Sales