Concrete coloring compositions and methods

Abstract

The present invention provides acidic compositions and methods that are adapted to impart color to cementitious or mineral substrate surfaces. Specifically, the present invention relates to acidic compositions and methods adapted to treat cementitious or mineral substrate surfaces that have the advantage of using a less corrosive acid-based solution. The acidic composition incorporates species including a weak base in equilibrium with a conjugate acid. The presence of such species moderates the corrosive behavior of the acid while still allowing excellent coloring action to occur.

1 .- 24 . (canceled) 
     
     
         25 . A method, comprising:
 (a) obtaining a composition derived from ingredients including (i) at least one metal salt that is a Lewis acid and that imparts a color to a surface of a cementitious or mineral substrate when the composition is in contact with and reacts with the surface; (ii) a weak base, wherein the conjugate acid of the weak base has a pKa less than 7 and greater than the pKa of the first acid;   (b) wetting the surface with the composition; and   (c) permitting the composition to react with the substrate surface and develop color.   
     
     
         26 . The method of  claim 25 , wherein the substrate comprises a fiber cement building product. 
     
     
         27 . The method of  claim 25 , wherein the metal salt comprises a FeCl 2  salt. 
     
     
         28 . The method of  claim 25 , wherein in the metal salt comprises a CuCl 2  salt. 
     
     
         29 . The method of  claim 25 , wherein the weak base can decompose upon application to the substrate into one or more components that comprise another base. 
     
     
         30 . The method of  claim 25 , wherein the weak base can decompose upon application to the substrate into one or more components that have a vapor pressure greater than 0.01 psi at 25° C. 
     
     
         31 . The method of  claim 25 , wherein the ingredients further comprise a MnCl 2  salt. 
     
     
         32 . The method of  claim 25 , wherein in the weak base comprises urea. 
     
     
         33 . The method of  claim 25 , wherein the one or more metal salts comprise at least one of a chloride, sulfate, nitrate, nitrite, phosphate, or phosphonate salt of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, aluminum, magnesium, or barium. 
     
     
         34 . The method of  claim 25 , wherein the composition further comprises a metal ion complexing agent. 
     
     
         35 . The method of  claim 25 , further comprising the step of neutralizing the colored surface. 
     
     
         36 . The method of  claim 25 , further comprising the step of: applying an at least partially transparent protective coating over at least a portion of the colored surface. 
     
     
         37 . The method of  claim 25 , further comprising the step of: applying a hydrophobic resist to the surface prior to application of the composition. 
     
     
         38 . A stained cementitious or mineral substrate prepared according to the method of  claim 25 . 
     
     
         39 . A stained cementitious or mineral substrate prepared according to the method of  claim 26 . 
     
     
         40 . A system, comprising:
 (a) a cementitious surface; and   (b) an aqueous composition in contact with the surface so that the composition can react with the surface and develop color, the composition derived from ingredients comprising (1) at least one metal salt that is a Lewis acid and that imparts a color to a surface of a cementitious or mineral substrate when the composition is in contact with and reacts with the surface; (ii) a weak base, wherein the conjugate acid of the weak base has a pKa less than 7 and greater than the pKa of the first acid.