This disclosure relates to an inorganic-organic metal phosphate ceramic coating from the reaction of an inorganic phosphate of the formulas (i) A.sub.m(H.sub.2PO.sub.4).sub.m.Math.nH.sub.2O or (ii) AH.sub.3(PO.sub.4).sub.2.Math.nH.sub.2O; where A is ammonium or an m-valent metal element; m=1, 2, or 3; and n is 0 to 25; and at least one metal oxide or hydroxide represented by the formula B.sub.2mO.sub.m or B(OH).sub.2m, where B is a 2m-valent metal; and m=1 or 1.5; thereof; and at least one polymer capable of reacting with at least the one metal oxide or hydroxide; or a first organic precursor combined with the inorganic phosphate and a second organic precursor combined with the at least one metal oxide or hydroxide, the second organic precursor configured to chemically react with the one or more first organic precursor.

Process for treating a porous dental zirconia block with a coloring solution, the process comprising the steps of providing a porous dental zirconia block having two opposing surfaces, surface U and surface L, treating the upper surface U of the porous dental zirconia block with a coloring solution A.sub.1, wherein the coloring solution is provided with a volume VA.sub.1, turning the porous dental zirconia block around, treating the lower surface L with a coloring solution A.sub.2 which is provided with a volume VA.sub.2. wherein the coloring solutions A.sub.1 and A.sub.2 comprise a solvent and coloring ions, wherein the volume of at least one of the coloring solutions A.sub.1 or A.sub.2 is applied in portions, wherein the following condition is met: Vo=V.sub.AX, with x2, with Vo being the overall amount of coloring solution used to infiltrate the porous dental zirconia block.

Process for treating a porous dental zirconia block with a coloring solution, the process comprising the steps of providing a porous dental zirconia block having two opposing surfaces, surface U and surface L, treating the upper surface U of the porous dental zirconia block with a coloring solution A.sub.1, wherein the coloring solution is provided with a volume VA.sub.1, turning the porous dental zirconia block around, treating the lower surface L with a coloring solution A.sub.2 which is provided with a volume VA.sub.2. wherein the coloring solutions A.sub.1 and A.sub.2 comprise a solvent and coloring ions, wherein the volume of at least one of the coloring solutions A.sub.1 or A.sub.2 is applied in portions, wherein the following condition is met: Vo=V.sub.AX, with x2, with Vo being the overall amount of coloring solution used to infiltrate the porous dental zirconia block.