Knowledge about glass
Hand blown glass
Hand-blown glass is an ancient craft, invented by craftsmen in Syria about 2,000 years ago.
The process of hand-blown glass is as follows:
1 Pick
After the quartz sand and various color forming accessories are processed by high temperature, they become liquid, and the blowing master uses a picking rod to pick out a small piece of material in the material pool.
2 Blow the bubbles
The blower will pick out the glass and blow a small ball (like a small light bulb) through the pick rod.
3 Blow cannon
Another blower puts the blown bubbles into the material pool, then dips some liquid into the open mold, and blows out the desired shape of the mold. (This process requires blowing workers to have many years of blowing foundation before taking up the post)
4 Heat and control the temperature
After the blown mold is formed, there is a cup body, and the bottom of the cup body should continue to be processed, so the temperature can not be lowered, so this part should be heated and controlled.
5 Stretch
After baking the sticky material under the cup body at high temperature, make it into a cup stick and control the size according to the requirements. No ruler is used, the craftsman relies on the "visual" experience to make it, and the visual error is accurate to the required range. This process is the biggest difference between hand-blown glass and machine-made glass.
6 Base
Once you've pulled it up, you're gonna make the base of the cup. First pick a little material to stick to the end, stick good material after the excess cut off, and then use the splint tool to make the bottom of the cup.
7 Annealing
After pinching the bottom, the cup is basically formed, and then put into the annealing kiln for annealing treatment, this step is to reduce the stress of the cup
8 opening
After removing the stress, when the cup cools down, there is excess waste at the mouth of the cup, the upper part is cut according to the required size after measuring by the scale, and the glass knife is pulled around the cup and then roasted with the fire, the excess part falls off by itself.
9 Grinding
After the step, the mouth of the cup is easy to cut people, so it is necessary to smooth the mouth of the cup evenly on the electric water grinding stone.
10 oven
Heat the rim of each cup over high heat to soften the edges before smoothing them.
11 Inspection of Packaging
The inspector inspects each molding cup and selects it according to the quality requirements. After inspection, the cup is scrubbed, packed and stored by the packer.
In the process of hand-blown glass, due to the slow flow of hot glass paste, the air between the glass blocks can not come to the surface and naturally form bubbles, which is normal, and is also an important feature of the visual difference between hand-blown glassware and machine-made glassware. And artists also use bubbles to express the life texture of glass, and bubbles have become a part of appreciating handmade glass art!
A reminder:
Handmade glass products have bubbles within 2mm, internal feather patterns, and slight cup rotation patterns, which are normal process phenomena, and are not workmanship defects and quality problems.
Why hand-blown glass?
1, compared with a single mechanism of transparent material, inflexible and lack of fastness. The transparent material of hand-blown glass products can be supplemented with various decorations, rich in color, changeable in shape, light in appearance, with streamlined beauty, and hidden natural vitality of bubbles and water ripples, which is better fastness.
2, the output of the mechanism is high, usually a medium production line can reach tens of thousands or even hundreds of thousands of daily production, but there is no manual technology content. Each production link of each hand-blown glass product is manually completed, the output is low, usually the daily output of each production team is hundreds, but each product contains the unique skills of the craftsman and the work of carving.
3, the mechanism of the product more to meet the use of consumer functions, lack of ornamental, low value. The reason why hand-blown glass has a high value is that it not only has practical functions, but also contains the expression of the craftsman's mind. Under the skillful manual interpretation, glass is no longer a cold instrument, it has temperature, personality, and can convey a different message to the owner.
Crystal glass
Crystal glass is made of silicon and lead oxide boiled together, because of its high permeability, can be made into a variety of crafts and favored. The European Union standard divides the crystal glass into three kinds: lead-free, medium lead (lead oxide content of 24%) and high lead (lead oxide content of 36%).
However, scientific studies have shown that long-term exposure to metal lead and acidic substances can produce chemicals that are harmful to the human body. Therefore, the relevant departments of the European Union have explicitly banned the production of lead crystal glasses since 2000.
Now it uses the high-quality potassium carbonate purified from oak ash and integrated into the quartz sand glass solution to form another crystal glass, that is, potassium glass, also known as "forest glass", and in one stroke surpassing the lead crystal glass and becoming the best crystal glass in the world.
Crystal glass products are low expansion coefficient material, not resistant to high temperature, not resistant to sudden cooling and heat.
A reminder:
Do not use lead crystal glassware containing wine, fruit juice, carbonated beverages, soda. Do not pour boiling water directly into it.
How to distinguish ↓
Common glassware
Crystal glassware
Lead-free crystal glass products
The color is relatively dull;
Poor refractive index;
The work is not very fine;
Feel not smooth enough;
Some have bubbles;
Soft tapping sounds dull;
The price is relatively affordable.
The color is bright;
Strong refractive index;
Exquisite workmanship;
Good hand feel;
Like crystal;
Gently tapping has a crisp metallic sound;
The price is higher.
Perfect display of refractive properties of metal glass;
The sound of tapping is more pleasant and pleasant, rich in the reputation of "music cup";
Better toughness, impact resistance;
Safer as a tableware;
It's expensive.
Colored glass
Various colored glasses can be made by adding a small amount of glass coloring agent when melting glass.
Copper oxide or chromium oxide produces green color;
Cobalt oxide produces blue color;
Manganese dioxide produces purple;
Tin dioxide or calcium fluoride produces a milky white color;
Uranium compounds produce yellow-green fluorescence;
Colloidal selenium produces red jade color;
Colloidal gold produces red, reddish purple, or blue;
Cuprous oxide produces red, green or blue;
Ferrous compounds produce green, black in large amounts;
Iron compounds produce yellow.
The glass will react with the acid and base, and the color in the glass will also react together, and the ingredients in the color need to be particularly wary.
A reminder:
Do not use colored glassware to serve vinegar-mixed dishes, and do not use alkali to clean.
High borosilicate glass
High borosilicate glass (also known as hard glass) is a kind of glass with sodium oxide, boron oxide and silicon dioxide as the basic components, in which the boron content is 12.5~13.5% and the silicon content is 78~80%, which belongs to the high temperature resistant glass in borosilicate glass. High borosilicate glass has a very low coefficient of thermal expansion, which is (3.3±0.1)×10-6/K, about one-third of that of ordinary glass, and can withstand dramatic temperature changes of 200 degrees. Even if broken by rapid or uneven temperature changes, high borosilicate glass cracks tend to be larger rather than crushed.
Compared with ordinary glass, high borosilicate glass, non-toxic side effects, its main performance indicators are up to international ISO standards: acid resistance, alkali resistance, water resistance, excellent corrosion resistance, with good thermal stability, chemical stability and electrical properties, so it has chemical erosion resistance, thermal shock resistance, good mechanical properties, withstand high temperature and other characteristics. Its good performance has been widely recognized by all walks of life in the world, Germany, the United States and other developed countries have been more widely promoted.
High borosilicate glass is widely used in solar energy, chemical industry, aerospace, military, medical packaging, electric light source, craft jewelry and other fields, can be made into lamps, telescope, stage light reflection cup, washing machine observation window, microwave oven plate, heat-resistant tea set and tableware, solar collector tube and other products.
A reminder:
To purchase glass tableware, please consult the business first whether it is resistant to sudden cooling and heat, whether it can be used in microwave ovens, refrigerators, dishwashers, disinfection cabinets.
Tempered glass
Tempered glass is the ordinary annealed glass first cut into the required size, and then heated to about 700 degrees close to the softening point, and then rapid and uniform cooling is obtained.
Feature one: Security
When the glass is damaged by external forces, the fragments will become small particles similar to the honeycomb, which is not easy to cause serious harm to the human body, so it is called "safety glass".
Characteristic two: high strength
The impact strength of tempered glass of the same thickness is 3 to 5 times that of ordinary glass, and the bending strength is 3 to 5 times that of ordinary glass. However, tempered glass has the possibility of self-explosion (its own rupture), according to industry experience, the self-explosion rate of ordinary tempered glass is 1 to 3‰.
Feature three: Thermal stability
Tempered glass has good thermal stability, can withstand the temperature difference is 3 times that of ordinary glass, can withstand the temperature difference of 300℃.
Tempered glass is often used in architectural decoration industry (doors and Windows, etc.), furniture manufacturing industry (glass coffee table), home appliance manufacturing industry (color TV, etc.), electronic instrument industry (mobile phone, etc.), automobile manufacturing industry (windshield), daily products industry (glass cutting board, etc.), special industry (military glass).