It is generally accepted that the ultra-violet light initiates an electron exchange between the manganese and iron ions. This changes the manganese compound into a form that causes the glass to turn purple.
It is manganese that will cause glass to turn purple if exposed to the sun for a period of time. My parents collected all kinds of items and we went to old dumps where they would dig for bottles. My Mother would then put some of the bottles in the sun to get them to turn purple.
From 1885 to 1914, manganese dioxide was used as a clearing agent by glass makers to make sure the glass remained clear. However, when exposed to the sun over time, the manganese dioxide in the glass will cause the glass to turn a purple tint. The main source of this clearing agent was Germany.
VIOLET (or PURPLE), uniting the "wisdom" and "love" symbolized by blue and red, is the symbol of justice and of royalty. PURPLE also stands for suffering and mystery and was the glassman's color for black, expressing negation, mourning, and death. When set forth with white, it stands for humility and purity.
Neodymium Glass (365nm / 395nm)
Neodymium glass (sometimes referred to as Alexandrite glass), changes color according to different lighting conditions. The glass appears lilac (or sometimes pink) in natural sunlight or yellow incandescent light, and smoky blue in fluorescent/white light.
true bright pink, like true bright purple, are ultra rare. Most purple sea glass is actually “sun” purple – in the old days manganese was added to glass as a clarifying agent, and manganese turns purple when exposed to UV rays – like those in sunlight.
Typically, pieces are made with low levels of uranium, meaning anywhere from trace amounts to 2%. However, some pieces have been found to be made up of 25% uranium. The uranium was added for the fluorescent effect it created.
Manganese-decolored glass that has undergone a color change due to exposure to the ultraviolet rays of the sun is variously known as sun- colored amethyst (SCA), solarized amethyst, solarized purple, or irradiated glass.
As for the type of glass used, if it's opalescent (where more than one color is present), then it was likely made after 1880. If it's amber or green low-grade glass, known as “slag,” then it was probably made in the early 1900s.
For the radiation to turn quartz purple, the quartz must contain trace amounts of iron. The color change is due to the fact that the radiation exposure results in an oxidation of the iron impurities (Fe+3 to Fe+4) which changes the absorption spectrum.
It is simply caused by alkali (soluble salt) being leached from the glass by slightly acidic water and then forming fine layers that eventually separate slightly or flake off causing a prism effect on light bouncing off and passing through the surface which reflects light differently, resulting in an iridescent ...
Because it takes so long, some people expose the glass to UVC lamps in a box at high intensity for 3–4 weeks to get them to change from clear to lavender.
Manganese is one of the oldest glass additives, and purple manganese glass was used since early Egyptian history. Manganese dioxide, which is black, is used to remove the green color from the glass; in a very slow process this is converted to sodium permanganate, a dark purple compound.
If they set glass out and it turned purple, it proved to them and to their customers that the glass was, indeed, made prior to ca. 1915 when most, but not all, glass companies ceased using manganese and substituted selenium as the clearing agent.
It is generally accepted that the ultra-violet light initiates an electron exchange between the manganese and iron ions. This changes the manganese compound into a form that causes the glass to turn purple.
Pink and red (cranberry) glass is typically the most valuable and was made using gold oxide, while blue (made using cobalt salts), green (uranium), and yellow or amber (sulphur) tend to command lower prices.
Sea glass is essentially broken glass from discarded items that have been polished and shaped over 20 years and up to 200 years by waves and weather. The legality of collecting sea glass depends on where you are located. It is illegal to collect sea glass on beaches located within U.S. state parks.
Is "sun-purpled" glass a good investment? On the contrary, it is tantamount to purchasing a piece of damaged glass and the value is decreased as though it had a serious crack or chip.
Historically, for African Americans, the purple glass is a symbol of burials in African American cemeteries. You carry a purple vessel with water in it and smash the glass vessel on a tombstone.
From circa 1943 until 1958, because of the events of World War II and the Cold War, U.S. officials did not allow the production of uranium glass since the government had banned uranium salts from commercial use. Only after uranium oxide was deregulated did the U.S. government allow uranium glass to be manufactured.
The best practice when approaching vintage glassware is to steer clear from using it on a daily basis, and don't store things in it for a long period of time, Dr. Kosnett recommends.
Ancient glass that has been buried over centuries often develops an iridescent surface. This is due to the interaction of elements in the base glass with the soil in which it was buried. Today, iridized surfaces can be produced using two methods: fuming and reducing.