guide to patination

A BEGINNERS GUIDE TO PATINATION

There are an enormous range of possibilities open to an artist or designer wanting to experiment with patinated finishes on metals (especially COPPER and it’s various ALLOYS). It could be argued that there are sometimes too many options available and that the depth of choice can make it more difficult for the artist to make a good decision. Ultimately though, one of the main attractions of using bronzes and similar alloys is the ability to apply so many distinct finishes to the metal's surface. It must therefore fall to the artist to exercise some degree of ‘editorial discipline’ over their choice of a patina. The fundamental challenge for any artist or designer is to select a finish that compliments each individual sculpture or cast design – a finish that remains in keeping with the nature of the artwork.

One point of particular issue is the attention given to unusual PATINA finishes. The ability to produce exotic effects is a point some foundries choose to labour in their promotional material. Although there is nothing particularly wrong with this, it is perhaps worth questioning how often an exotic finish genuinely compliments the sculpture it is applied to. Does the artist ultimately want the viewer to apply their critical faculties to the sculpture as a whole, or simply admire the originality of the patina?

It is important that any artist regularly working with cast sculpture, acquires an understanding of the basic principals and techniques used in patination processes. Likewise, any aspiring foundry technician should first develop a sound grounding in the basic, traditional patinas before they look to expand into more unusual techniques and effects, which ultimately may prove to be of only very limited or occasional use.

The patination techniques and recipes described over the next few pages detail the most basic and commonly used. Their common use reflects the fact that the chemicals needed are usually easily obtained, generally straightforward to prepare and use, resulting in predictable effects that have long term stability.

The preparation and application of a patinated finish can be a deceptively subtle undertaking. In this respect, keep in mind that following any written ‘recipe’ to the letter is a poor substitute for long term experimentation and experience. Judging the correct temperature of a metal surface to achieve the successful development and adhesion of a patina, can be especially difficult. With perseverance though, good results should be achieved before too long.

Anyone wishing to experiment with patination for themselves is advised to exercise extreme caution in the handling and use of chemical compounds. Consider the following precautions to be the minimum required. Look up specific OHS information about the materials and processes you are intending to use.

• Wear suitable protective clothing, overalls, aprons, chemically resistant gloves and an appropriately rated impact face shield or glasses.

• Ensure adequate ventilation and extraction of fume, wear appropriate respiratory equipment. Be especially aware of the potential for reduced oxygen levels through fume displacement within restricted spaces.

• Consider others in the vicinity and never use or store chemicals in a domestic environment.

• Read, understand and follow supplied MATERIALS SAFETY DATA SHEETS (MSDS). These documents set out procedures for the safe handling, storage and use of individual compounds. Dispose of waste material safely and responsibly. Keep neutralising agents to hand in case of spillage, and set up an emergency eye wash station adjacent to the work area.

• Take great care not to get chemical names mixed up (potassium sulphide – ammonium sulphide and so on).

• Don’t eat, drink or smoke when using patination compounds. Never keep chemical preparations in containers likely to be used, or that have previously been used for food or drink. After work, store compounds and any leftovers in a locked ‘chemicals only’ cupboard.

• Always add the chemical compound to water, never water to the chemical – unless specifically instructed otherwise. Start with small quantities of added in chemical, and increase the strength of the solution according to need by testing.

• Exercise extreme caution when adding in two or more compounds to a common solution. Beware of violent reactions and effusive or toxic fume. Think through what you are doing before you act and double-check for safety implications. If in any doubt – don’t proceed.

• Try to avoid working alone. Ensure the availability of immediate assistance, especially when working within confined spaces (even if wearing assisted breathing apparatus).