- Easy Test
- XRF Analysis
- Drinking from Crystal Stemware
- What is Lead Crystal?
- Leaded Glass
- Lead Content
- Raw Material
- Heavy Metals
- Soda Lime Glass
The easiest way to tell if it’s lead crystal glassware or ordinary glass is to take a butter knife or other metal utensil and gently tap the glass; if it makes a drawn-out ringing sound, it is more than likely crystal; if it sounds more like a short dull “clink,” it’s glass.
Ordinary glassware (soda-lime glass) does not “ring” like lead crystal glassware because, with the addition of lead, the glass absorbs more energy when tapped and causes it to resonate/vibrate creating what some call a “ping.”
In addition, lead crystal weighs more than regular glass; there’s no mistaking the two.
Due to its acid nature, a tablespoon of white wine vinegar when let stand for twelve hours in a regular glass, wine goblet, or any other glass object can show the presence of lead (if present) when tested with a common 3M lead test kit.
This can show that lead may be present, but not parts per million (ppm.)
See XRF Test below.
Lead oxide added to molten glass is what gives leaded glass “crystal” the refractive qualities; glass without added lead has a refractive index of 1.5.
Leaded glass has a refractive index of 1.7 which is the point where light can be separated into its colors and therefore has a prismatic (rainbow) effect.
You can also have your item tested by a lab that would run an XRF (x-ray fluorescence) analysis of wine glasses, glass bowls, or other crystal pieces; an analysis costs approximately $50 per test.
The XRF will detect the presence of lead, if any, and how many parts per million/ppm lead the crystal contains.
The XRF analysis can also detect any other heavy metals and the presence of hazardous elements in a crystal object as well.
Two other options are to take a suspected piece, pulverize it and melt it down to find the lead content, or subject the item to strong acids that will ruin the piece.
Drinking from Lead Crystal Stemware
Drinking from lead crystal glasses from time to time should not sound any alarms, according to recent scientific studies, as the contents are not usually in the container long enough for the lead to leech out into the product being consumed.
While vintage glassware and leaded crystal glass can add a touch of elegance, their usage should be reserved for special occasions such as the Holidays and special drinks, but not for daily use.
Acidic and alcoholic beverages should not be left in leaded crystal decanters for any prolonged period of time to reduce the risk to human health; in fact, many leaded decanters have been shelved and replaced with something such as Crystalline Glass.
Leaving the product in lead crystal beverage containers such as a decanter can result in higher lead concentrations and increased health risk due to lead exposure.
If the product is consumed within a day, using leaded crystal stemware/glass should be fine; with that being said, there have been tests that showed traces of lead leaching out into the product at two days.
What is Lead Crystal?
First of all, there is no crystal in lead crystal; it is a term that goes back a long time, many years.
Lead crystal is glass with lead added to it.
Glass is an amorphous solid; it has no crystalline structure, such as quartz does.
When referring to lead glass, the term “Crystal” has remained in use because of its historical value, and that the word “lead” can leave consumers with negative connotations.
The term Crystal glass originates from the Venetian word Cristallo that described the rock crystal that Murano glassmakers imitated; it dates to the 15th century.
Lead has been used in the making of some glass since The Egyptian Bronze Age. The addition of lead oxide to silicon dioxide (silica sand) made the molten glass softer, more workable; it flowed easier at a lower temperature and allowed the glassmaker more time.
The lead made the glass denser, heavier, clearer, and brilliant form of glass with fewer impurities and higher refractive qualities.
In Europe, lead glass artifacts with varying amounts of lead have dated to the tenth century; some are as much ⅔ lead to ⅓ silica/sand.
Before 1969 lead crystal was assumed to have a 36% amount of lead, and then lead levels dropped to 24% after concern grew of lead poisoning.
Lead Crystal must contain 24% lead to be considered lead crystal; more than 30% lead is known as Full Lead Crystal.
Glass with 10% or more lead is considered “Fine glass.”
In manufacturing lead crystal, sand (silica), soda ash, limestone, and lead are used in the recipe, resulting in a high refractive index.
Lead-free crystal glass is produced using the same ingredients as above, but the lead is substituted with barium oxide and may include zinc oxide and or potassium oxide.
Barium oxide imparts luster and increases the refractive index in the glass without having to add lead.
Zinc oxide is added as a flux which reduces the melting temperature.
Potassium can increase the refractive quality and clarity of crystal glass.
Toxic metals such as cadmium (think red, yellow. and orange colors,) chromium(green,) and lead concentrations have been found in the enamels applied to decorated glassware and wine and beer bottles.
Tests have shown that decorated glassware in The United States for young children contained dangerous amounts of toxins and far exceeded acceptable federal levels; flakes of paint from the outside of the glassware have been shown to come off the glassware in everyday use.
Learn more about lead from the Environmental Protection Agency by clicking here EPA
With Inert and impermeable qualities, soda glass contains about 70% silica, 15% sodium oxide (soda ash), 9% lime with smaller amounts of ingredients, makes up about 90% of the type of glass in use today.
Soda-lime glass is used in the glass industry to make everything from windows, bottles, and Ball Mason jars to most contemporary glassware and glass food storage.
Click here to learn more about Soda-Lime glass.
It’s easy to tell the difference between “Crystal” and regular glass; it’s beautiful stuff, but I wouldn’t make a habit of drinking out of it. On the other hand, I know few people who don’t appreciate the look of fine leaded crystal glass, and they look beautiful when displayed on shelves, in a cabinet.
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