One of the most distinguishing factors that give an old piece of jewellery its magic is its patina. This is some sort of tarnish or imperfection that has developed on the jewellery's metal. The metal's distinctive patina is the result of age and wear-and-tear. Technically, it is a coating of different kinds of compounds such as carbonates or oxides that form over the surface in time.
In the world of antique collecting, patina is highly valued. However, patina can be rubbed off after repeated washing or during jewellery repair. Since it takes a lot of time to regenerate patina, some collectors opt to add patina to the piece. Applying patina restore the original look of an antique or simulate antiquity in objects that are newly made. The antique-collecting community calls the application is called as the process of distressing.
Restorers utilise a wide variety of household and commercial chemicals to reapply or simulate patina. The basic premise in the technique of distressing is that certain chemicals react to the elements in the jewellery piece, producing the desired "ageing." The resulting patina depends on the chemical and how the metal reacts to it. For example, when exposed to chlorides, copper alloys such as bronze produce a greenish patina. The same alloys turn brown when exposed to sulphuric compounds. Other chemicals used to apply patina on metals include ammonium sulphide (which produces a blue-black sheen), liver of sulphur (which generates a brown-black patina), and cupric nitrate (which produces a blue-green tint), or ferric nitrate (which generates an ageing shade of yellow-brown).
Applying chemicals to produce patinas is not limited to jewellery. Deliberate patination is also applied on artworks. For instance, antique canvas paintings may be subjected to chemicals that give them shades of deep blues, greens, matte sandstones, and reds. Frame surfaces may be enhanced through oiling and waxing and application of clear coats. Burn marks on wood can be reapplied by lightly burning the material then quickly extinguishing it off, creating a sooty appearance.
If a collector has time and patience, he can apply patination to his collections naturally but in an accelerated manner. For example, antique irons and pots can be soaked in salt water and left out in the sun, causing rust to form quickly.
Repatination is quite important in preserving a piece's appearance and character. That's because the reduction of patina may also decrease the value of the piece. However, according to appraiser Reyne Haines, a repatinated piece is usually worth more than significant imperfections in the patina.
However, it would still cost less than an antique jewellery that still has its original patina.
