New glass is thinner and gives a whiter reflection than old glass. You can test this by holding the edge of a white card against the glass. If the card and the reflection are the same white color, the mirror was made after 1850. If the reflection is more yellow or gray, the glass was made before 1850.
Start with the year you were born, then simply subtract your age. The result is your 'mirror year'. For example, if you've recently turned 25 then subtract that number from the year 1989 to get a mirror year of 1964. Why do that?
You can inspect the mirror yourself to discover a variety of telltale signs, such as unusual embellishments, a signature by the craftsman and mint condition, that point toward a rare piece. If you feel your vintage or antique mirror might be especially valuable, get it appraised by a professional to confirm its worth.
Moisture breaks down the bond between the glass and the backing product causing the silver layer to chip off leaving the mirror with black spots or edges wherever the silver layer is damaged. This can also break down due to age, incorrect glass cleaners, or faulty manufacturing.
What Causes Black Spots on Mirrors? Some of the spots on mirrors are opaque areas of damage on the reflective coating, and others are from the backing that's been scraped or eaten away (so you can see through past the back of the mirror).
Victorian mirrors
Mirrors of this period often adopted styles of periods past, and were known for being grand or elaborate. Victorian mirrors are usually the most heavily carved, with bold decoration. The Victorians didn't solely favour gilt, but often opted for woods such as mahogany or rosewood.
Antique mirrors are commonly made of glass coated by silver, gold, or chrome. Outside of the use of tin and mercury in Venetian antique mirrors, which causes a mirrors to develop a crystalline appearance as it ages, there are other telltale signs of a mirror's age.
An antique mirror is any mirror made at least 100 years ago. Modern designers sometimes make mirrors that look antique because the look of old mirrors never goes out of style.
Antique glass is typically thicker and heavier than modern glass to accommodate for the process of hand-blown glass production.
Mercury mirrors reflect less light and have a bluish appearance, while silver mirrors look more yellow. This effect can be enhanced by placing a thin piece of paper over the mirror, which will appear paler and brighter over the silver mirror (Hadsund 1993).
Why are mirrors so expensive? Mirrors are always made of high-quality glass. This is reflected in the longevity and accuracy in the functioning of mirrors. Hence, the price of the end product naturally shoots up.
Tip: Place a rod (pen or toothpick) on the mirror. If the point touching the mirror looks like it is directly “touching” its reflection, the glass layer is thin enough and the mirror is probably modern. On the other hand, if the point is separate from its reflection, then it is probably mercury (prior to 1835).
Mirrors made of glass backed with a reflective coating of tin amalgam first came into general use in the 16th century. Production ceased around 1900.
During the 19th century, craftsmen created windows and other glass products by manually spinning molten glass on a blow pipe, which produced glass with a wavy quality.
Mirroring (re-silvering) is a very wet process. In order to re-silver a mirror, you will have to remove it from its frame. This is a good time to see if the frame itself needs to be strengthened or repaired. The best time to do this is after you have carefully removed the mirror.
Silvering is the chemical process of coating a non-conductive substrate such as glass with a reflective substance, to produce a mirror. While the metal is often silver, the term is used for the application of any reflective metal.
Distressed mirrors are sometimes referred to as antiqued or even vintage mirrors.
Findings: The earliest known manufactured mirrors (approximately 8000 years old) have been found in Anatolia (south central modern-day Turkey). These were made from obsidian (volcanic glass), had a convex surface and remarkably good optical quality.
Silver Coated Glass Mirrors
In 1835, Justus Von Leibig started using silver instead of mercury to coat the glass, thus creating the silvering process that we still use today. Glass itself is not very reflective, which is why the silvering is needed.
(a) Stand in front of mirror near it and look to your image. (i) If the image is erect and of same size and size of image does not change even if you move forward or backward, the mirror is a plane mirror. (ii) If the image is erect and diminished one, the mirror is a convex mirror.
These were made of polished bronze shaped into flat round discs—in representation of the sun-god Re—with handles of wood, metal or ivory. Likewise, in China, an unearthed cast bronze mirror has been dated as early as 2000BCE.
The earliest manufactured mirrors were pieces of polished stone such as obsidian, a naturally occurring volcanic glass. Examples of obsidian mirrors found in Anatolia (modern-day Turkey) have been dated to around 6000 BCE.
By 1800 mirrors with frames were important decorative pieces. Some frames were made of silver, ivory or tortoiseshell, veneered with expensive woods or covered in needlework or beads. Carved wooden frames were made to match other household decorations, and soon a mirror over the mantel was almost required.