The patina is applied by heating the entire sculpture evenly with large propane torches and spraying or brushing on various chemicals to produce the color on the surface. Most of the patinas that I use are layered and require heating the piece more than once. One of the great things about bronze is its reactivity to a wide variety of chemicals. Greens and browns are most common, and there are many recipes for those. I usually apply a base coat of liver of sulphur or birchwood casey and use nitrates to get my colors.
Some sculptures call for more exotic colors.
Finally, the sculpture is heated once more to eliminate any moisture from the surface and wax is applied. If you have ideas or questions about my work, or have project in mind, feel free to contact me. Sculptors, foundrymen, and friends of sculpture can ask questions and post comments at the Sculptors' Forum and find helpful links to other artists' resources through my Links Directory .