Observing and inspecting glass under a microscope (2023)

overview

Due to the variety of properties of glass, scientists have been able to modify and improve it by cutting, painting, polishing and more. This allows glass to be used as lenses, glassware, mirrors, and even as optical fibers (transmitting high-speed data over optical fibers). However, glass has many more uses in various industries around the world.

Ordinary glass is made from ingredients such as silica, bleaching powder, calcium oxide, and various alkali metals. However, it should be noted that there are different types of glass, composed of many numbers of different components. Flint glass (used in electric lights and camera lenses) is made of potassium carbonate, while pyrex glass (used in various laboratory equipment) is made primarily of barium and sodium silicates.

Other types of glass include:

• Photochromic glass
• Lead crystal glass - made of potassium carbonate, silica and lead oxide
• Xena Glass - Made of Zinc Borosilicate and Barium Borosilicate
• Fused Silica - Made of Silicon
• Crown Glass - made of Potassium Oxide, Silicon and Barium Oxide

*Glass can also be modified in various ways for specific uses. Tempered glass, for example, is made from sand, lime, and soda carbonate, and when heated it breaks into cubes rather than shattering. Bulletproof glass, on the other hand, is composed of ionoplast polymers, ethylene vinyl acetate or polycarbonate.

A brief history of glass

Glass has been used in one form or another throughout human history. Before humans learned to make glass, humans used obsidian (a natural volcanic glass) for knives, jewelry, and arrows. However, over time, humans have learned to create glass from the various elements around them.

Based on archaeological findings, it is generally believed that the first use of glass was around 3500 BC. was made. Invented by the Egyptians and those in eastern Mesopotamia. After 2,000 years, these civilizations were able to modify glass to create a variety of glassware that can be used. In other parts of the world (except Eurasia and North Africa), people didn't start making glass until around 1500 AD.

This is despite evidence of human presence as early as 3500 BC. Production of glass (artificial glass), this only happened between 500 and 700 BC. Significant industrial development in different regions of the world (Syria, Egypt, Levant, etc.). This has led to the manufacture of various types of glass products, including containers and various glassware.

As the industry continued to flourish, new glassmaking equipment was invented, making the production process easier and cheaper. One of the best examples is the bellows invented by Syrian artisans in the first century. Over time, new technologies were developed, not only for glass production, but also for the production of various consumer goods (light bulbs, bottles, pipes, window panes, etc.).

glass research

The analysis or study of glass requires the use of various techniques including X-ray techniques, optical spectrometers, etc.Microscopy. Usually this is done to examine/study the structure and various properties of the glass.

These technologies are used in different fields for different purposes. In archaeology, by examining glass using the techniques described above, researchers can not only learn more about the various ingredients used to make glass, but also determine its origin and period of manufacture.

Studies have shown that samples from Persia and Mesopotamia consist of plant alkaloids, which in turn consist of more potassium and magnesium oxides. In forensics, on the other hand, such studies/examinations allow experts to find out the source of cullet, its refractive index (using a hot stage microscope) and its suitability for certain situations, while collectors use these techniques To determine whether the sample is genuine.

glass experiment under microscope

In this experiment, you will observe and examine three types of glass under a microscope.

These include:

• obsidian
• Ordinary glass

Purpose

At the end of these labs, you should be able to:

• Prepare Glass Samples for Microscopy
• Learn how to analyze glass with a microscope
• Identify the structure/morphology of glass under the microscope

obsidian

As mentioned earlier, obsidian is a glass/rock formed by volcanic activity.

Usually, it forms when lava (volcanic activity) cools rapidly, causing the atoms to arrange themselves into an amorphous structure. Depending on where it comes from, obsidian can range in color from black or dark brown to brown (such as mahogany obsidian) and mottled white (snowflake obsidian), which is black with white flecks.

Require

• obsidian
• glass slide
• microscope coverslip
• water and a container
• Kannada Balsam am Oder See - Harz
• Grinding wheel
• continuous blade

meeting minutes

The purpose of rock/glass preparation is to produce flakes that can be viewed under a microscope.

This involves the following steps:

·put stones in water to hydrate

·Carefully cut the stone into slices 0.5 to 1 mm thick using a continuous-edged blade

·Carefully remove any material produced during the cutting process of the abrasive wheel

·Glue obsidian discs to clean glass slides using Lakeside resin or Canada balsam

·To further reduce the thickness of the glass/stone, use a rotating metal winder to grind with an abrasive of approximately 10 microns. This reduces the thickness of the sample to half the original thickness

·Remove the obsidian from the slide, flip it over and glue it back onto the slide - so the first sanded surface is now glued to the slide

·The disc was milled again to a thickness of approximately 0.08mm. However, if the feta is still opaque, you can go ahead and (lightly) grate it

·Cover the slide with Canada Balsam or Lakeside resin to allow the sample to be placed between the slide and the coverslip

·Place the slide on the microscope stage for observation

Windshield and normal glass

Depending on the purpose of the analysis, different techniques are used to inspect windshields and ordinary glass. One of these techniques involves the use of a microscope.

Require

• Glass samples (plain/common or windshield)
• Stereomicroscope
• a pair of tweezers
• glass transparency

meeting minutes

Carefully remove a small piece/fragment from the jar using tweezers and place it on a glass slide or paper (colored paper can be used).

*Macro microscopes have larger fields of view and longer working distances than stereo microscopes.

*Stereo microscopes can also be used. In contrast to macroscopic microscopes, stereomicroscopes provide true stereoscopic images.

Mount glass samples (obsidian, windshield, and plain glass) in the microscope

*Obsidian is also analyzed ascompound microscope。

meeting minutes

·Turn the stage adjustment knob to lower the stand to accommodate slides

·Place the slide on the microscope frame and secure it with stage clamps (the clamps are located on the stage).

·Rotate Turret to Position Low Magnification Lenses

·You can carefully adjust the tent to the proper position with the tent adjustment knob

·Gently turn the course and trim knobs until the image is clear

·You can adjust the amount of light by adjusting the condenser. This allows you to set the proper light intensity to get a clear image of your sample

·Lower the stage again and rotate the turret to switch to a higher magnification and observe the slide. This allows you to compare lower and higher magnification images

·Finally, lower the stand to remove the bracket

monitor

Under the microscope, obsidian appears black with some hydration streaks that have been shown to be caused by glacial wear. On the other hand, windshields and normal glass (up to ✕6 and ✕40) show clear fracture surfaces.

Depending on the glass, pits and scratches may also appear on the glass surface. Use a macro microscope (available in ✕100 and ✕120 magnifications) for a larger field of view, making scratches and dents more clearly visible.

*In addition to compound, stereo and macro microscopes, students can compare the surfaces of different types of glassfluorescenceandpolarizationMicroscopic examination.

diploma

As mentioned earlier, there are different types of glass used for different purposes. Using compound, stereo, and macro microscopes, students can examine and compare the surfaces of different types of glass, including stained glass, and compare their appearance.

While it may not be possible to observe glass components (the components that make up the glass being examined) with this microscope, viewing the surface can provide information such as scratches and give students an idea of ​​where the specimen was found. .

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references

Bekir Karasu, Oguz Bereket, Ecenur Biryan and Deniz Sanoglu. (2017). The latest progress in glass science technology.

Brian Cady (2001). Forensic investigative analysis and interpretation of glass and paint.

David Whitehouse. (2012). Glass: A Brief History.

Jay A. Siegel. (2015). Forensic Chemistry: Principles and Applications (Forensic Science Focus) 1η Έκδοση

Link

https://www.researchgate.net/publication/229563463_Perspectives_on_the_History_of_Glass_Composition

https://ncfs.ucf.edu/research/physical-evidence/glass/

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