DarkRange55
Enlightened
- Oct 15, 2023
- 1,256
There are two different ordinary uses of the word crystal. The first ordinary use of the word crystal is a orderly arrangement of molecules of a single molecule. A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. Two common crystals found in almost every bodies homes are salt crystals or sugar crystals. Crystal means that atoms of a material are arranged in a repeating pattern. The other ordinary use of the word crystal is a special type of glass. Glass is a generic name, while, crystal is a subcategory of glass, made in the same manner as glass but with different materials. Hence, all crystal is glass, but not all glass is crystal. Glass is whats called an amorphous solid, which means its atoms are all haphazardly arranged. Historically, also known as flint glass due to the original silica source, the word "crystal" was used to describe glass with high amounts of lead oxide. Lead crystal is prized for its durability and decorative properties, even if it does not necessarily possess a crystalline structure. It is referred to as crystal because, years ago, the Italian term "cristallo" was used to refer to Murano glassimitations. So with cristollo glass, beyond its rarity the value was largely tied to how clear this glass is combined with its light refractive qualities which were particularly enhanced when viewed by the flickering flames of candles and lanterns.
In the U.S., glasses with a lead monoxide content of 1 percent are automatically categorized as crystal. In the European Union, labeling of crystal products is regulated by Council Directive 69/493/EEC, which defines four categories, depending on the chemical composition and properties of the material. Only glass products containing at least 24% of lead oxide may be referred to as "lead crystal". Products with less lead oxide, or glass products with other metal oxides used in place of lead oxide, must be labeled "crystalline" or "crystal glass." The technique of adding lead oxide (in quantities of between 10 and 30%) improves the appearance of the glass. The brilliance of lead crystal relies on the high refractive index caused by the lead content. The main thing that affects the clarity of cheap glasses is iron (specifically 2+ iron if I remember correctly). One alternative material is crystal glass, in which barium oxide, zinc oxide, or potassium oxide are employed instead of lead oxide. Lead-free crystal has a similar refractive index to lead crystal. Zinc is much less toxic than lead, and barium doesn't bio accumulate the way lead does. Crystal can be heated at lower temperatures than glass because of the lead and potassium carbonate in the composition. This allows for the glassblower to more easily work the material and make it thin. The additional chemicals also help the material to remain strong while being stretched further than glass. However, nowadays, a number of ordinary soda glass manufacturers produce very thin plain glasses which are not crystal. Metal oxides make the glass melted a lower temperature, should tend to make it cool through the transition temperature more slowly, which would give it more time to smooth out, but it would not be a big effect. If metals leach out they do change the flavor. I would be surprised if enough metal leached out to significantly affect the roughness beyond the nanometer scale, which would not have much impact on bubbles. Basically, everything always leaches to some degree – sometimes it's just not enough to worry about (for instance, clean water and diamond). Even lead plumbing is sort of okay if the water is not acidic at all... But why take a chance – don't use lead! (Or Mercury, or uranium, or cadmium). "Glass typically has sharp cuts, while crystal will have clean, rounded cuts." This statement is quite superficial. There is some truth in it, only if the designer wishes to have soft cuts on the glass. Thus, there are production modes the glass cutters apply to achieve sharp edges on crystal glassware. Traditional cut crystal is cut by hand on diamond or stone wheels on a lathe to create the desired pattern. The wheels abrade the glass leaving a white 'ground' finish to the glass. This needs to be polished to a high sheen to finish the piece. This is achieved by immersing the lead crystal in a mixture of undiluted Hydrofluoric and Sulphuric acid. The consequent exothermic reaction can achieve temperatures in excess of 80 degrees Celsius, which are required for the polishing process, which is essentially a dissolving of the glass. This results in soft edges in the clear crystal glass. The crystal glass has a higher refractive index, so it is better at refracting sunlight into its constituent colors. Crystal is often used for prisms, chandeliers, anything where you want the glass to be 'sparkly' or colorful. This recipe is also used for ornamental drinking ware and special bottles used to contain, for example, brandy. Crystalglassware does nothing to improve the flavor though it does enhance the visual presentation. Lead crystalglassware is generally for show rather than serious wine appreciation. I would say "little effect" rather than no effect. Droplets might stick slightly more on one kind of glass than the other, so there probably is a detectable effect if you're willing to spend enough on equipment. Different glasses also have different thermal conductivities which can slightly affect the temperature of the liquid and thus its viscosity. Thermal conductivity of glasses typically varies between 0.5 – 1.5 W/(m K), the highest being for fused silica and lowest for leaded glass.
In the U.S., glasses with a lead monoxide content of 1 percent are automatically categorized as crystal. In the European Union, labeling of crystal products is regulated by Council Directive 69/493/EEC, which defines four categories, depending on the chemical composition and properties of the material. Only glass products containing at least 24% of lead oxide may be referred to as "lead crystal". Products with less lead oxide, or glass products with other metal oxides used in place of lead oxide, must be labeled "crystalline" or "crystal glass." The technique of adding lead oxide (in quantities of between 10 and 30%) improves the appearance of the glass. The brilliance of lead crystal relies on the high refractive index caused by the lead content. The main thing that affects the clarity of cheap glasses is iron (specifically 2+ iron if I remember correctly). One alternative material is crystal glass, in which barium oxide, zinc oxide, or potassium oxide are employed instead of lead oxide. Lead-free crystal has a similar refractive index to lead crystal. Zinc is much less toxic than lead, and barium doesn't bio accumulate the way lead does. Crystal can be heated at lower temperatures than glass because of the lead and potassium carbonate in the composition. This allows for the glassblower to more easily work the material and make it thin. The additional chemicals also help the material to remain strong while being stretched further than glass. However, nowadays, a number of ordinary soda glass manufacturers produce very thin plain glasses which are not crystal. Metal oxides make the glass melted a lower temperature, should tend to make it cool through the transition temperature more slowly, which would give it more time to smooth out, but it would not be a big effect. If metals leach out they do change the flavor. I would be surprised if enough metal leached out to significantly affect the roughness beyond the nanometer scale, which would not have much impact on bubbles. Basically, everything always leaches to some degree – sometimes it's just not enough to worry about (for instance, clean water and diamond). Even lead plumbing is sort of okay if the water is not acidic at all... But why take a chance – don't use lead! (Or Mercury, or uranium, or cadmium). "Glass typically has sharp cuts, while crystal will have clean, rounded cuts." This statement is quite superficial. There is some truth in it, only if the designer wishes to have soft cuts on the glass. Thus, there are production modes the glass cutters apply to achieve sharp edges on crystal glassware. Traditional cut crystal is cut by hand on diamond or stone wheels on a lathe to create the desired pattern. The wheels abrade the glass leaving a white 'ground' finish to the glass. This needs to be polished to a high sheen to finish the piece. This is achieved by immersing the lead crystal in a mixture of undiluted Hydrofluoric and Sulphuric acid. The consequent exothermic reaction can achieve temperatures in excess of 80 degrees Celsius, which are required for the polishing process, which is essentially a dissolving of the glass. This results in soft edges in the clear crystal glass. The crystal glass has a higher refractive index, so it is better at refracting sunlight into its constituent colors. Crystal is often used for prisms, chandeliers, anything where you want the glass to be 'sparkly' or colorful. This recipe is also used for ornamental drinking ware and special bottles used to contain, for example, brandy. Crystalglassware does nothing to improve the flavor though it does enhance the visual presentation. Lead crystalglassware is generally for show rather than serious wine appreciation. I would say "little effect" rather than no effect. Droplets might stick slightly more on one kind of glass than the other, so there probably is a detectable effect if you're willing to spend enough on equipment. Different glasses also have different thermal conductivities which can slightly affect the temperature of the liquid and thus its viscosity. Thermal conductivity of glasses typically varies between 0.5 – 1.5 W/(m K), the highest being for fused silica and lowest for leaded glass.
