Stains and Dyes, or should I say...

 Acid Stains are not a paint, coating, or sealer. Acid stained  concrete is a coloring process involving a chemical reaction on a  cementitious material. A solution made with water, acid and inorganic  salts reacts with minerals already present in the concrete. Acid stains  are made from hydrochloric acid, wetting agents and metallic ions. When this solution is placed on concrete it colors the concrete by chemically combining the metallic ions with the particles in the concrete to form  oxides. The result of this reaction is color.  Chemical stains can be applied to new or old, plain or colored concrete surfaces. Although they are often called acid stains, acid is not the ingredient that colors the concrete. Metallic salts in an acidic, water-based solution react with hydrated lime (calcium hydroxide) in hardened concrete to yield insoluble, colored compounds that become a permanent part of the  concrete. Got all of that? Good! 

  Water-based penetrating concrete stains (dyes) can have distinct advantages over acid staining. There are many more colors and it works by penetrating the pores of  the concrete and creating a permanent stain that is vibrant in color with a variegated and translucent look.   Unlike acid stain, which is reactive and has a somewhat undetermined outcome, you can control the coloring and design with a water-based stain. This is done  by regulating the amount of stain you apply, the application method, as  well as the ability to accent with other colors. Water-based stains are also eco-friendly. They will not harm your skin, there are no toxic fumes or VOC’s to worry about, and they are  safe for vegetation. Water-based stains typically have a larger coverage rate than acid stains as well. 

  Acetone dyes, with their ease of  use, extensive palette, and vibrancy of color are creating a wave of popularity that is gaining momentum. Unlike acid stains, which react chemically with the calcium hydroxide in concrete, dyes are nonreactive and impart color by  penetrating concrete or other porous cementitious surfaces. Dyes are much smaller in particle size than chemical stains or acrylic stains, thus allowing for easier penetration and color saturation while leaving less residue on the surface. The small  dye particles fill the pores of the concrete and are very hard to remove, making dyes nearly as permanent as stains. Because there is  virtually no residue, minimal cleanup is required, greatly speeding the  application process.