Make sure the copper you are annealing is clean and free of any oily substance. This means beeswax, cut lube, and even the oils on your fingers. Wash the piece of copper with a good degreasing soap, rinse, let the water shed off the piece while holding it by the edges. Once the piece is devoid of moisture, lay it on the brick or heat resistant surface. Side note: I have a brick from a friend that lived in New Haven CT; his house is brick and built in 1912. He had bricks that he had reclaimed during a renovation. The brick has the year convexly detailed as part of the structure of the brick. Laying the copper pieces I am annealing on the convex numbers is instrumental. A brick can be a heatsink and capture the heat from the flame, which could divert the heat to the brick and take the heat away from the copper. The raised numbers serve as standoffs so the copper pieces are receiving the full heat of the flame.