A method for making an environmental barrier coating using a sintering aid comprising: combining at least water, and a primary transition material comprising mullite, BSAS, or a mullite/BSAS mixture to produce a transition layer slurry; applying the transition layer slurry to a ceramic component; drying the transition layer slurry to a ceramic component; infiltrating a sol-gel solution into the applied transition layer slurry, the sol-gel solution being an aqueous solution of a water soluble sintering aid or an organic solvent solution of a solvent soluble sintering aid, the sintering aid being a sintering aid that lowers the temperature needed to densify the applied transition layer slurry, the water soluble sintering aid being chosen from the group consisting of rare earth nitrate, rare earth acetate, rare earth chloride, the solvent soluble sintering aid being chosen from the group consisting of solvent soluble rare earth sources; combining at least water and a primary outer material comprising BSAS to produce an outer layer slurry; applying the outer layer slurry to the component having the applied transition layer slurry; and sintering the applied transition layer slurry and the applied outer layer slurry to produce the environmental barrier coating having at least a transition layer and an outer layer formed from the applied transition layer slurry and the applied outer layer slurry, respectively, wherein the transition layer contains the primary transition material and a secondary material, the sintering aid increases a rate of diffusion of the primary transition material such that surface area reduction occurs within the transition layer at lower temperatures than would occur absent the sintering aid, and the sintering step forms the secondary material in at least the transition layer as a reaction product of the sintering aid with the mullite, the BSAS or the mullite/BSAS mixture of the primary transition material, and the secondary material is chosen from the group consisting of rare earth oxides, rare earth disilicates, rare earth monosilicates, rare earth elements, rare earth containing aluminosilicate glasses, rare earth and alkaline earth containing aluminosilicate glasses, rare earth aluminates, and combinations thereof. combining at least water, and a primary transition material comprising mullite, BSAS, or a mullite/BSAS mixture to produce a transition layer slurry; applying the transition layer slurry to a ceramic component; drying the transition layer slurry to a ceramic component; infiltrating a sol-gel solution into the applied transition layer slurry, the sol-gel solution being an aqueous solution of a water soluble sintering aid or an organic solvent solution of a solvent soluble sintering aid, the sintering aid being a sintering aid that lowers the temperature needed to densify the applied transition layer slurry, the water soluble sintering aid being chosen from the group consisting of rare earth nitrate, rare earth acetate, rare earth chloride, the solvent soluble sintering aid being chosen from the group consisting of solvent soluble rare earth sources; combining at least water and a primary outer material comprising BSAS to produce an outer layer slurry; applying the outer layer slurry to the component having the applied transition layer slurry; and sintering the applied transition layer slurry and the applied outer layer slurry to produce the environmental barrier coating having at least a transition layer and an outer layer formed from the applied transition layer slurry and the applied outer layer slurry, respectively, wherein the transition layer contains the primary transition material and a secondary material, the sintering aid increases a rate of diffusion of the primary transition material such that surface area reduction occurs within the transition layer at lower temperatures than would occur absent the sintering aid, and the sintering step forms the secondary material in at least the transition layer as a reaction product of the sintering aid with the mullite, the BSAS or the mullite/BSAS mixture of the primary transition material, and the secondary material is chosen from the group consisting of rare earth oxides, rare earth disilicates, rare earth monosilicates, rare earth elements, rare earth containing aluminosilicate glasses, rare earth and alkaline earth containing aluminosilicate glasses, rare earth aluminates, and combinations thereof.