A method for improving surface roughness of an environmental barrier coating comprising: providing a component having a plasma sprayed environmental barrier coating; applying a slurry to the environmental barrier coating of the component, the slurry comprising a transition layer slurry or an outer layer slurry; drying the environmental barrier coating having the applied slurry; and sintering the component to produce a component having an improved surface roughness wherein the slurry comprises: water; a primary transition material, said primary transition material is selected from the group consisting of a rare earth disilicate or a doped rare earth disilicate or a primary outer material, said primary outer material is selected from the group consisting of a rare earth monosilicate or a doped rare earth monosilicate and at least one slurry sintering aid selected from the group consisting of iron oxide, gallium oxide, aluminum oxide, nickel oxide, titanium oxide, boron oxide, alkaline earth oxides, carbonyl iron, iron metal, aluminum metal, boron, nickel metal, iron hydroxide, gallium hydroxide, aluminum hydroxide, nickel hydroxide, titanium hydroxide, alkaline earth hydroxides, iron carbonate, gallium carbonate, aluminum carbonate, nickel carbonate, boron carbonate, alkaline earth carbonates, iron oxalate, gallium oxalate, aluminum oxalate, nickel oxalate, titanium oxalate, solvent soluble iron salts, solvent soluble gallium salts, solvent soluble aluminum salts, solvent soluble nickel salts, solvent soluble titanium salts, solvent soluble boron salts, and solvent soluble alkaline earth salts; or wherein the slurry comprises: at least 1 wt% water; from 0.1 wt% to 72 wt% of the primary transition material or the primary material; from 0.1 wt% to 59.3 wt% Lnb rare earth metal slurry sintering aid, which refers to a sub-set of rare earth metals having a melting point below 1450°C; from 0.1 wt% to 20.6 wt% SiO 2 slurry sintering aid and optionally any organic processing aids. providing a component having a plasma sprayed environmental barrier coating; applying a slurry to the environmental barrier coating of the component, the slurry comprising a transition layer slurry or an outer layer slurry; drying the environmental barrier coating having the applied slurry; and sintering the component to produce a component having an improved surface roughness water; a primary transition material, said primary transition material is selected from the group consisting of a rare earth disilicate or a doped rare earth disilicate or a primary outer material, said primary outer material is selected from the group consisting of a rare earth monosilicate or a doped rare earth monosilicate and at least one slurry sintering aid selected from the group consisting of iron oxide, gallium oxide, aluminum oxide, nickel oxide, titanium oxide, boron oxide, alkaline earth oxides, carbonyl iron, iron metal, aluminum metal, boron, nickel metal, iron hydroxide, gallium hydroxide, aluminum hydroxide, nickel hydroxide, titanium hydroxide, alkaline earth hydroxides, iron carbonate, gallium carbonate, aluminum carbonate, nickel carbonate, boron carbonate, alkaline earth carbonates, iron oxalate, gallium oxalate, aluminum oxalate, nickel oxalate, titanium oxalate, solvent soluble iron salts, solvent soluble gallium salts, solvent soluble aluminum salts, solvent soluble nickel salts, solvent soluble titanium salts, solvent soluble boron salts, and solvent soluble alkaline earth salts; or at least 1 wt% water; from 0.1 wt% to 72 wt% of the primary transition material or the primary material; from 0.1 wt% to 59.3 wt% Lnb rare earth metal slurry sintering aid, which refers to a sub-set of rare earth metals having a melting point below 1450°C; from 0.1 wt% to 20.6 wt% SiO 2 slurry sintering aid and optionally any organic processing aids. <EOS>