Everything you have always wanted to know about glass

1. How is the prescribed strength of eyeglasses achieved?

Refraction can be varied by the refractive index of special types of optical glass, as well as by grinding, and thus can be used as a compensating strength for defective vision, namely in the form of eyeglasses. There are over 120 different types of optical glass.

2. What are the main components of glass? In what ratio are the main components mixed?

about 60 parts sand = 24%
about 180 parts potassium carbonate = 74%
about 5 parts lime/chalk = 2%

These components are listed in the first formulation handed down from Assyria (about 640 BC). In order to obtain coloring and other properties, additives, metals and rare earths are used.

3. How is glass produced?

Glass is melted in vats with fireproof cladding, which nowadays are heated by oil, gas or electricity, and is then

a) drawned, rolled (flat glass)
b) pressed, blown (hollow glass)

and, if necessary, subjected to further processing:

a) coated
b) imprinted
c) polished
d) drilled
e) faceted
f) frosted
g) tempered/pre-stressed

Learn more about the fascination of producing special glass here!

4. How is opal glass made?

Opal glass is made by frosting clear glass, or made as frosted translucent glass or as clear glass with white screen printing. Clear flat glass, which is coated and melted together with a thin opal glass (white) during drawing, is called flashed opal glass. Covers for lighting units for glare-free lighting, display cases and indicator glasses in instruments are only some of the applications.

5. How is colored glass made?

Glass that is colored throughout can be produced by adding coloring materials, subsequent colored coating or transparent imprinting is also possible

6. At what temperature does glass begin to melt?

Depending on the type of glass and on the glass batch composition, the melting temperature is between approximately 1000 °C and 1600 °C (1832 °F and 2912 °F).

7. When was glass first produced?

Historically, glass production is known to have existed in ancient Egypt around 8000 BC, as well as in Mesopotamia and Mycenaea, China and Northern Tyrol

8. How is reflective glass made?

Reflective glass can be produced by vaporizing, coating or imprinting with metallic materials, such as silver, gold, copper, etc.

9. Why does glass protect against UV rays?

Special glass or vaporized glass has a blocking filter in the UV range, which reduces or blocks the penetration of UV rays.

10. How many different types of glass are available from SCHOTT?

SCHOTT manufactures over 50,000 different articles with over 400 types of glass.

11. Why is a glass fiber lamp not hot?

Before light enters the fiber, an infrared blocking filter prevents the passage of heat until the light exits at the end of the glass fiber.

12. How is glass cut?

In a laser cutting process developed by SCHOTT, the laser beam precisely heats a specific line on the glass followed by a cold jet of air or an air/liquid mixture. These thermally induced tensions cause a precise fissuring of the glass. The result are cutting edges of the highest quality.

13. In which areas are fiber optics used?

Illumination (optical fibers and light sources for indoor and outdoor use, show-cases, decoration, autocar, airplane) Fiber light display (fiber-optic illuminated displays for advertisement signboards, information boards Industry (optical fibers and line lights for customized industrial components) Cold light sources (for the use in laboratories, photography, microscopy) Medicine (fiber rods/ fiber cones for medical devices and dental practice) Traffic control technology (traffic light signal transmitters on motorways, airports and in tunnels)

14. Why are fiber optics particularly safe and particularly protective (e.g. for items in display cases)?

Cold light through fiber optic lighting offers the advantage that valuable items in display cases are not heated and thus do not oxidize, dry out or turn yellow.

15. How are ceramics produced from glass?

A glass specially mixed with nucleus formers and melted for ceramization is ceramized in a time/temperature process. At the end of this process a mixed glass/crystal structure is created, which has the desired qualities, e.g. of a cooking surface.

16. How long does glass need to cool?

To prevent stresses in the material, glass has to be brought slowly to the ambient temperature. This is done in a time-controlled annealing oven. Depending on the quantity/type of glass, this "annealing time" - which actually is a controlled "heating reduction" - ranges from hours to months.

17. What is the temperature of the annealing ovens?

At the start of the process, "annealing ovens" have a temperature level corresponding to the production temperature/forming temperature, and at the end of the process, that of the ambient temperature. This is an individual temperature/time profile dependent on the product/type of glass.

18. What does a glassblower´s pipe look like?

19. What is cast glass?

Cast glass designates a family of glass produced in a casting production process. It includes raw glass, figured glass, horticultural cast glass, wire-reinforced glass and wire-reinforced figured glass. It is also possible to produce colored cast glass.

20. What is processed flat glass?

Processed flat glass is floatglass which is additionally
cut drilled provided with processed edges facetted (bevelled edges) screenprinted laminated tempered assembled/ processed to a glued sandwich construction
in order to fulfill different additional needs.