A method for making an environmental barrier coating using a sintering aid comprising: applying a bond coat layer to a ceramic component; combining at least water, and a primary transition material comprising a rare earth disilicate, or a doped rare earth disilicate to produce a transition layer slurry; combining at least water, and a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate to produce an outer layer slurry; combining at least water, and a primary compliant material comprising BSAS or a rare earth doped BSAS to produce a compliant layer slurry; applying at least the transition layer slurry, and any one or more of the outer layer slurry or the compliant layer slurry, to the component; drying the component; infiltrating a sol-gel solution comprising an aqueous solution of a water soluble salt sintering aid, or an organic solvent solution of a solvent soluble salt sintering aid into the applied transition layer slurry; and sintering the component to produce the environmental barrier coating having at least the bond coat layer, a transition layer and any one or more of an outer layer or a compliant layer; wherein during sintering a reaction between the primary materials and the sintering aid results in the transition layer comprising a porosity of from 0% to 15% by volume of the transition layer, the outer layer comprising a porosity of from 0% to 30% by volume of the outer layer, and the compliant layer comprising a porosity of from 0% to 30% by volume of the compliant layer; and wherein the applied transition layer slurry is sintered to produce the transition layer after infiltrating the sol-gel solution but prior to applying the any one or more of the outer layer slurry or the compliant layer slurry. applying a bond coat layer to a ceramic component; combining at least water, and a primary transition material comprising a rare earth disilicate, or a doped rare earth disilicate to produce a transition layer slurry; combining at least water, and a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate to produce an outer layer slurry; combining at least water, and a primary compliant material comprising BSAS or a rare earth doped BSAS to produce a compliant layer slurry; applying at least the transition layer slurry, and any one or more of the outer layer slurry or the compliant layer slurry, to the component; drying the component; infiltrating a sol-gel solution comprising an aqueous solution of a water soluble salt sintering aid, or an organic solvent solution of a solvent soluble salt sintering aid into the applied transition layer slurry; and sintering the component to produce the environmental barrier coating having at least the bond coat layer, a transition layer and any one or more of an outer layer or a compliant layer; wherein during sintering a reaction between the primary materials and the sintering aid results in the transition layer comprising a porosity of from 0% to 15% by volume of the transition layer, the outer layer comprising a porosity of from 0% to 30% by volume of the outer layer, and the compliant layer comprising a porosity of from 0% to 30% by volume of the compliant layer; and wherein the applied transition layer slurry is sintered to produce the transition layer after infiltrating the sol-gel solution but prior to applying the any one or more of the outer layer slurry or the compliant layer slurry.