How to distinguish crystal from glass? How is glass produced?

In our daily life, we often come into contact with various types of glass materials, in addition to the traditional flat glass, there are super white glass, high borosilicate glass and other glass materials with special properties, as well as insulating glass, laminated glass and other common materials. In order to let you further understand the difference between crystal and glass, as well as the production method of glass, we collected information and arranged this article, hoping to help you quickly distinguish crystal and glass.

1、 How to distinguish crystal from glass

A way to quickly identify crystal and glass

Lead glass imitation crystal and high refractive index rare earth glass imitation Amethyst are common in the market

(1) Touch gemstone with palm or mouth, natural crystal has cool feeling; glass imitation crystal has warm feeling

(2) Check with polarizer: when rotating 360 degrees under the polarizer, the natural crystal has four light and four dark changes, and the glass imitation crystal has no change

(3) Check with dichroism: Natural Amethyst has dichroism, glass imitation crystal has no dichroism

(4) Feldspar with hardness of 6 is used as test stone to mark the gem on the feldspar. Crystal can mark the same mark on the feldspar, and glass imitation crystal can slip on it. If there is no feldspar, it can also be directly marked on the glass. Crystal can mark the mark on the feldspar, and glass imitation crystal can mark the same mark on the feldspar

(5) Test with thermal conductivity meter: when the thermal conductivity meter is adjusted to 4 green grids, the crystal can rise to 2 color grids, but the glass imitation crystal product does not rise, when the area is large, it will rise to 1 color grid

2、 How are glasses made

Glass cup is a kind of glass cup made of high borosilicate glass, which is fired at more than 600 degrees. It has the characteristics of high transparency, strong sense of crystal, wear resistance and so on

The powder and clinker mixed according to the glass composition are put into the crucible kiln or tank kiln (see glass furnace) for melting. After melting, they are clarified into a uniform glass liquid without bubbles, stones and stripes, and then cooled to the viscosity range suitable for the corresponding forming method

1) Blow molding

There are two ways: manual blowing and mechanical blowing

1. In the process of manual molding, the material is picked up from the crucible or the furnace inlet with a hand-held blowpipe and blown into a device shape in the iron mold or wood mold. The smooth round products are blown by rotary blowing method; the products with convex and concave patterns on the surface or with non-circular shape are blown by static blowing method. The products with colorless material are first picked and blown into bubbles, and then the colored or opacified materials are picked by bubbles and blown into a device shape are called sleeve blowing, Different colors of natural melt flow can be blown into natural scenery utensils; stained with ribbon opacified material, can be blown into wire drawing utensils

2. Mechanical molding is used to blow large quantities of products. The blowing machine can automatically close the iron mold to blow into the shape of the vessel after receiving the material, and then remove the cap after demoulding to form the vessel. Pressure blowing can also be used to make the material into small bubbles (rudiment) first, and then continue to blow into the shape of the vessel. It has higher blowing efficiency and better quality than the blowing machine alone

2) Press forming

During manual forming, the material is picked manually and put into the iron mold to drive the punch, press into the shape of a device, and demould after solidification

Automatic production of mechanical forming, large batch and high efficiency. Press forming is suitable for small and large end products that can exit punch, such as glass cup, glass candlestick, glass jar, glass bottle, etc

3) Freeform

It is also called molding without mould. It is repeatedly baked and modified or thermally bonded in front of the kiln by manual picking. Because it does not contact with the mould, the glass surface is bright and the shape and line of the products are smooth. The finished products are also called kiln glass products

4) Centrifugal molding

When the material is in the rotating mold, the centrifugal force generated by the rotation makes the glass unfold and close to the mold, and then it is taken out after solidification. It is suitable for the molding of large glassware with uniform wall

Related concepts

crystal

Quartz crystal is a colorless and transparent large quartz crystal mineral. Its main chemical composition is silica, and its chemical formula is SiO2. Crystal is colorless, purple, color, green and smoke, glass luster, transparent to translucent. The crystal has a density of 2.56-2.66 g / cm3 and a refractive index of 1.544-1.553, almost within this range. The crystal has a dispersion of 0.013 and a melting point of 1713 ℃. When it is pure, it will form colorless and transparent crystals. When it contains trace elements such as Al and Fe, it will be purple, color and tan. After irradiation, trace elements will form different types of color centers and produce different colors, such as purple, color, tan and pink. The inclusions containing associated inclusion minerals are called inclusion crystals, such as hair crystals, green ghosts, etc., and the inclusions are rutile, tourmaline, actinolite, mica, chlorite, etc.

Crystal glass

Crystal glass is called man-made crystal, because the natural crystal is very few and not easy to exploit, can not meet the needs of people, man-made crystal glass was born. Crystal glass is made of silicon and lead oxide (the subsequent lead-free crystal uses other materials, such as potassium oxide, barium oxide, etc.) together. Each factory has its own secret recipe to make the crystal particularly shiny. The clarity depends on the polishing technology and quality. Because of its high permeability, it can be made into various handicrafts.