When blowing glass, a certain amount of lead is added, commonly known as crystal glass. The crystal glass is the best for drinking wine. After adding a large amount of metal lead, the microscopic surface structure of crystal glass is not as smooth and smooth as ordinary glass. This structure gives the wine body more area to contact the air and accelerate the wine oxidation process. Can accelerate sobering up while drinking. It can be observed through the microscope that the crystal surface has more concave and convex surfaces. During the shaking process of the wine glass, the wine will help to break the wine molecules and release the aroma; using it to hold champagne, the performance of the bubbles will be better, and the uneven surface on the glass It can hold the foam of the wine body for a long time. The foam is the soul of champagne. The crystal wine glass can delay the release process of champagne foam.
Those containing 24% lead or above are called full lead crystals, and those below 24% are called lead crystals. The advantage of adding lead is heavier, textured, more transparent, clear and bright; and the refractive index of this glass material is very high, it looks like crystal clear and translucent, there is a metallic sound when tapping, beautiful and pleasant. The price of this glass material is relatively expensive, and it is generally used in handicrafts.
We can also distinguish between crystal glass and ordinary glass in terms of sound, feel and gloss.
1. Sound, tap the glass body with your fingers. Since crystal glass can make a metallic sound, it sounds more pleasant.
2. Feel, crystal glass is relatively thick and heavy, which is obviously different from ordinary glass.
3. Tongue licking. Crystal glass will feel cold and cool even if it is touched with the tip of the tongue in summer, otherwise it will not.
4. Gloss, the refractive index of crystal glass is particularly good, and it can absorb the gloss. Putting the glass in the sun will release beautiful luster no matter from which angle it is viewed.
Since our country does not currently have a national standard for crystal glass, many companies are manufacturing according to EU standards. The EU standard divides crystal glasses into three types: lead-free, medium-lead and high-lead. The lead oxide content of the medium lead glass reaches 24%; the lead oxide content of the high lead glass reaches 36%. Crystal glass containers are produced in accordance with EU standards and should be safe for the human body. However, due to the lack of standards in China, it cannot be ruled out that the production of individual manufacturers is arbitrary and the product quality is difficult to guarantee.
Because the acid resistance of the crystal glass with lead is not enough, when the strong acid is encountered, the metal lead will dissolve. In recent years, lead-free crystal glass has sprung up, and its price is higher than that of lead-containing crystal glass.
In lead-free crystal cups, barium, zinc, titanium and other substances are used to replace metal lead. The following methods can be used to distinguish between lead and lead-free glass:
1. Light weight: Leaded crystal glass products are slightly thicker than lead-free crystal glass products.
2. Listen to the sound: Beyond the metallic sound of lead-containing crystal glass, the sound of lead-free glass is more pleasing to the ears, and has the reputation of "music" cup.
3. Look at toughness: Lead-free glass is more tough than lead-containing crystal glass, that is, impact resistance.
Lead-free crystal glass has poor low temperature resistance. If it is put directly into the freezer of the refrigerator, it is easy to freeze and crack.