I was in the fireplace store the other day asking about this sealant. The fireplace is gapped where the marble meets the frame. There was some sealant in there and it looks like it has pulled away from the edges. Is there a high heat sealant that exists in the 700-1000 degree range in white or black without going with a gasket sealer from the automotive store? 1 fireplace store said it exists but they don't carry it, however another said it does not. HD and Lowes have 500 degree sealant . TIA for any replys!!