66｜Glass Manufacturing Method, Forming Method, Processing Method 4

Hello everyone 🎵

We're talking about types of glasses. In the glass industry, until recently, the discussion around crystal was about whether it contained lead or not. Currently, with the exception of some manufacturers, leaded crystal is no longer produced. On the other hand, general customers often associate "crystal" with a high-end image. The meaning of crystal varies by generation in the glass industry, and it also differs from customers' perceptions. It's a bit complicated, but since "crystal" is a single word, I'll be discussing the composition of crystal this time.

Crystal glass is more premium and expensive than soda glass, but it excels in weight, metallic sound, clear color, and brilliance. Crystal glass, invented in the Middle Ages, was manufactured by adding lead oxide to the raw materials. While "lead" might conjure images of danger, lead oxide is a chemical compound and is harmless. It is strictly controlled by ISO and food sanitation law standards, so crystal glass can be considered safe.

However, to avoid using lead in the manufacturing process for the lead oxide raw material, many lead-free crystal glasses have been invented in recent years, and lead-free crystal is now the mainstream.

Crystals containing lead oxide can be divided into 3 types based on their lead oxide content.

1. Full Lead Crystal

This is crystal glass with a lead oxide content of 30% or more. It is the highest quality crystal glass, known for its luster, weight, and beautiful ringing sound. However, due to its nature, if more than 30% lead oxide is added, small bubbles will appear inside the glass. Manufacturers like Waterford Crystal in the UK call it "full lead crystal" precisely because of these bubbles, but general customers might wonder why a high-end crystal would have bubbles?

2. Lead Crystal

This contains between 24% and less than 30% lead oxide. This is common crystal glass. You might have seen labels or stickers indicating "24% PBO" or "24% Crystal." Kagami Crystal and some Czech manufacturers still produce it. Many manufacturers worldwide, such as HOYA Crystal and ARC in France, used to make it, but none currently do.

3. Semi-Lead Crystal

This contains between 10% and less than 24% lead oxide. It is called "semi-crystal" in the industry, and manufacturers like Toyo-Sasaki Glass still produce it.

Crystal without lead oxide is called Crystallyn. It was developed by adding metallic compounds other than lead oxide, such as barium, zinc, and potassium. Items containing 10% or more of these components, either singly or in combination, are called crystal glass or crystalline. They are defined separately from soda glass. In Europe, labeling regulations for product materials were established as EEC standards in the 1970s and are now continued as EU standards. Compared to soda glass, it has a higher refractive index and transparency, similar to lead crystal. It is generally considered an environmentally friendly glass. The composition and brand names vary among manufacturers.