Antique mirrors were often made from glass covered with a thin layer of metal, usually mercury or silver. Mercury was used because it is an excellent thermal and electrical conductor, and it forms a smooth, reflective mirror layer when sprayed onto a glass substrate. In addition, mercury is also relatively abundant and easy to use in a manufacturing process. However, the use of mercury is dangerous because it is a highly toxic chemical that can cause harm to human health and the environment.
The mirror through the ages
In ancient times, mirrors were carved out of mercury, and it was widely believed to be the most durable material available for their use. However, recent studies have shown that synthetic and metal-backed glass is better for use in today's home.
A mirror on a metal back
In the early Renaissance, metal-backed glass mirrors were made in Venice. They were made using a thin sheet of glass supported by a metal support. The glass was then covered with a layer of metallic silver. This process, which is still used today, was a precursor to the modern techniques used to make modern mirrors. Today it is often more interesting to buy a cheap baroque mirror that is new than to have it repaired.
Mirrors have been used for thousands of years. Early evidence suggests that mirrors were used for a wide variety of rituals and entertainment. They have also played an important role in archaeology, medicine and psychology. In the Middle Ages, mirrors were used in rarefied imperial rituals. They were also used for personal grooming and as part of household decoration.
Mirrors were also associated with steppe societies, including the Yin period of China and the Bactrian-Margiana cultures of northern Central Asia. Mirrors have been used as amulets to ward off evil spirits. They were also seen as a symbol of wealth, privileged lifestyles and social etiquette.
The first mirrors in the archaeological record were made from volcanic glass and obsidian. The first glass mirrors were made in the third century AD. The first mirror made with a metal support was produced in Lebanon in the first century AD.
In the early Renaissance, mirrors using tin-mercury amalgams were made in Venice. These mirrors were much more durable than glass mirrors and were resistant to all types of influences. They also offered a much whiter reflection than glass mirrors.
Metal-backed glass mirrors were also used in the seventeenth and eighteenth centuries. The metal alloys used to make these mirrors were usually made of tin and copper. These metal alloys were also highly polished to provide a reflective surface. However, the alloy was not as durable as Silver-Mercury amalgam. They were also more expensive.
Metal-backed glass mirrors were also used in the 19th century. A chemical process was developed to coat a glass surface with a layer of metallic silver. This process resulted in higher quality mirrors. This procedure has also been used in Belgium and Germany. However, the process was expensive and not perfect. If you have an antique mirror, you may want to have your mirror restored, abcpascal.fr offers this service, craftsmen are very few to offer this type of work.
Tin amalgam
Over the past decade, many studies have been conducted on Tin-Mercury amalgam in antique mirrors. Using a variety of spectroscopic techniques, a thorough understanding of the degradation processes of this alloy was achieved. The ultimate goal is to further understand these degradation processes and develop techniques to inhibit them.
The Tin-Mercure amalgam of antique mirrors consists of two phases. One is a liquid phase of 0 to 5% and the other is a solid phase of 0 to 20% by weight. Both phases are surrounded by a mercury-rich liquid phase of 0 to 20% tin. During degradation, these two phases are dissociated, resulting in a loss of material in the reflective glass area.
The Tin-Mercury alloy is inherently unstable. Its deterioration can be accelerated by contact with dust and wood panels. Therefore, special precautions are necessary for safe handling and disposal of amalgam mirrors.
AFM (atomic force microscopy) and SEM-ED (scanning electron microscopy with dispersive energy spectrometry) were used for the characterization of the amalgam of ancient mirrors. SEM images showed the different degradation products of amalgam.
The study also demonstrated that the tin-mercury alloy is a binary alloy, with two phases. The liquid phase consists of 95 to 100% by weight of mercury and contains 0 to 5% by weight. The solid phase is characterized by a crystalline phase with 81% tin and 20% by weight mercury.
The corrosion process in amalgam mirrors results in decreased adhesion to the glass, resulting in a loss of reflective power. This process also releases mercury vapor into the air. In addition, it forms tin oxides and tin monoxide.
These oxides form a crater around the amalgam drop. They are only visible when the mirror is backlit. In addition, the presence of hemispherical layers of tin oxides suggests a gradual corrosion process, involving cyclic phases.
The study also shows that the tin-mercury amalgam of mirrors is characterized by two distinct layers. The first layer is undegraded and consists of a layer 0.1 mm thick. The second layer contains a liquid phase layer rich in mercury and is characterized by X-ray diffraction. During degradation, the crystalline phase develops and the liquid phase evaporates.
Silver glass
Throughout the centuries, mirrors have been made from a variety of materials, including silver and obsidian. Unlike today's modern mirrors, early mirrors were not made from glass and were probably made of stone or clay water containers.
Unlike today's mirrors, these antique mirrors may have been integrated into the walls. They were also seen as magical devices that could predict the future. They were also buried with the elite dead.
In the Middle Ages, a small amount of mercury was rubbed on the glass. The process was similar to today's resilient process, although it was labor-intensive.
In the twelfth century, the technology behind the creation of a mirror gained a boost when a guild of mirror makers was formed in Nuremberg. It became the epicenter of the manufacturing mirror for several centuries.
Mercury is an extremely dangerous element, museum collections contain it and public health is studied.