The methods described below all have set recipes. One recipe is not interchangeable with the next, and a chemical that produces one colour own one recipe, likely produces another colour in a different technique. For this reason, sufficient knowledge and experimentation needs to be carried out by the Patineur.
This is by far the most widely employed technique. The results are instant, and in a world where time is money, all fine-art bronze foundaries utilise this method. The principle goes as such: the bronze is heated with a blow torch and a patina solution is applied to the surface. Depending on the heat and the concentrate of the patina mixture, along with the dabbing of the patina brush; colour is instantly developed on the surface. Each layer can be followed by a rinsing and a subsequent layer of a different sort.
The cold patina process is rarely used, but in large scale works, this is a preferred method – since heating is a tedious process. The surface of the metal can be completely cold or be standing outdoors in the sun, this is an adequate range of temperature to achieve colouration of the metal. A patina mixture can be applied sparingly with a cloth or generously with a brush, all depending on the chemical composition of the mixture.
This technique doesn’t get used much at all by fine art foundries, in-fact, unless the quantity of the sculpture edition is vast, this approach requires too much capital with a boring finish. The bronze gets immersed into a rich solution of chemicals which have a direct and uniform result on the surface of the metal. The benefits are that really deep / saturated colours can be achieved, and if the sculptor desires uniformity, this is also acquired. Unfortunately, its an expensive undertaking and requires many differing batches of patina baths to be really practical, and a common size sculpture to go into such a dipping process. This is a more industry developed approach, one that should really stay out of the fine-art world.
Buried / sawdust technique
This approach too requires a heavy investment since wood chips / sawdust / soil needs to be saturated with a patina mixture and brought into contact t=with the bronze surface for a sufficient amount of time, up to 2 weeks. The results can be really interesting, much like unearthed vessels form the ming dynasty, but once again – the resulting textures of the grain is imprinted on the surface, which can compete with the bronze texture itself.
Vapour / fume technique
This is a most exciting process. The clean – sandblasted bronze sculpture gets placed into an airtight container, where a chemical mixture will also be placed inside. Depending on the humidty, temperature and proximity to the ocean, results can differ greatly, not to mention the composition of the bronze alloy itself. As if by a purely alchemical process, the results can be an iridescent black to an ultra-marine blue, as-if by crystals, the fine texture of encrustation, that which evokes the ocean like quality of barnacles. Learning this process and being able to somewhat master it has been my nightmare and delight. Much can be said about this, but I have to thank a certain artist for giving me much freedom to explore – Lionel Smit himself.