Abstract: A method for closing holes in a ceramic substrate may include the steps of filling the holes with a paste including a ceramic filler material and an alumina powder suspended in an organic carrier; firing the substrate at a temperature sufficient to burn off the organic carrier, but lower than the melting temperature of the ceramic sealing material; maintaining the substrate at the burn-off temperature for a time period sufficient to burn off substantially all of the organic carrier; raising the temperature of the ceramic substrate to a sealing temperature sufficient to melt the ceramic sealing material, but lower than the melting temperature of the ceramic stabilizing material; maintaining the ceramic substrate at the sealing temperature for a time period sufficient to allow the molten ceramic sealing material to fill interstices in the hole; and cooling the substrate.