I was impressed by how vibrant the 22k gold decals looked on both raw terracotta clay and over-glazed surfaces. I fired the terracotta to cone 02, and the gold adhered, though less so where it was closer to the bottom shelf near the burners, which gave it a slightly withered finish. On over-glazed pieces, the decals fused perfectly during firing, resulting in a brilliant gold finish. I highly recommend these for a luxurious gold accent!