How To Observe Glass Under A Microscope

If you are interested in observing materials under a microscope, then chances are you have considered examining glass. 

Glass is a beautiful material known for its unique composition, which scientists are able to enhance with various techniques. Because of this, observing glass can tell you a lot about its construction and the materials used to make it.

How To Observe Glass Under A Microscope

But how do you observe glass under a microscope?

In the article below, we will explain how to observe glass with a microscope, whether that be obsidian or common crystal. We will also discuss the finer details of these experiments and the data they reveal. 

What Is Glass? 

Glass refers to a non-crystalline material that is both solid and transparent. Since its initial invention, glass has been used for various purposes, whether that be decorative items or technical applications.

Because of its many uses, glass has become a point of interest among scientists, which has allowed them to study the material and modify its composition.

For this reason, scientists use methods such as cutting to enhance the material, making it suitable for lenses, glassware, and mirrors. It can even be made into optical fibers, which are used to transmit data and information. 

However, this does not mean that glass is limited in its use, as the material is utilized in different ways across the world. 

In terms of composition, common glass is made from a combination of silica, bleaching powder, calcium oxide, and various alkaline metals. However, the substance can also be made with other materials depending on its function.

For instance, bulbs and camera lenses are made from flint glass, which contains potassium carbonate. While pyrex is made from barium silicate and sodium. 

Other notable kinds of glass include: 

  • Crown Glass: made from potassium oxide, barium oxide, and silica
  • Lead Crystal Glass: made from potassium carbonate, silica, and lead oxide
  • Quartz Glass: made from silica 
  • Xena Glass: made from zinc and barium borosilicate 
  • Photochromatic Glass

It’s also important to note that glass can be modified for certain uses, as tempered glass is made from a combination of sand, lime, and sodium carbonate.

This substance is then left on extreme heat until the material begins to break down into dices. It’s also possible to make the material bulletproof, which contains ionoplast polymers, ethylene vinyl acetate, and polycarbonate. 

Where Does Glass Come From? 

The history of glass can be connected to the start of human civilization, as the material has been used in various forms since its invention.

However, before the advent of man-made glass, humans would use a material called obsidian, which is a volcanic substance used to make glass and other items. 

However, this would all change when humans learned how to make man-made glass from the elements around them. 

Recent studies have shown that glass was first invented around 3500 BC, with its creation now being associated with the ancient cultures of Egypt and Mesopotamia.

How To Observe Glass Under A Microscope (1)

However, it took another 2000 years before these civilizations were able to modify the material, which made it suitable for vessels and other uses. In contrast, the material would not be made in Eurasia or Africa until 1500 AD. 

Despite this, it wasn’t until 500 – 700 BC that the industry started to grow, with the material becoming a prominent export in Syria and Greece. Because of this, different forms of glass were invented, which could be used to make vessels and decorative items.

It was during this time that new equipment was also introduced to make the manufacturing process easier and faster. 

A common example of this is the blowpipe, which was first invented in the 1st Century by a team of Syrian workers.

Over time, new techniques and methods were also developed, which allowed humans to produce glass for a variety of products, such as bulbs, bottles, tubes, windows, and doors. 

Why Observe Glass? 

The study and observation of glass requires the use of various tools and materials, which includes x-ray tech and optical spectrometers.

During the observation, you will also need an understanding of microscopy techniques, as this will make it easier to examine the material and investigate its composition and structure. 

These techniques are often used across various fields, which means you can use them to learn more about the material and its characteristics.

A common example of this can be found in archeological studies, where the techniques are used to determine the material’s components as well as the time period in which it was made. 

For instance, recent samples from Persia and Mesopotamia were shown to have consisted of more potassium and magnesium oxides, which could be attributed to alkali sourced from the natural environment. 

On the other hand, forensic scientists will use these techniques to determine the source of the material, as well as its refractive index.

In some cases, collectors and historians will also use microscopy to determine the value and authenticity of a piece, which is often measured by the materials used to make it. 

How To Observe Glass Under A Microscope

If you are still interested in observing glass under a microscope, then we have provided an experiment in the section below. 

This experiment will allow you to examine the composition of two different kinds of glass, these include the following: 

  • Obsidian 
  • Common Glass 

What Is The Objective? 

By the end of this experiment, you will be able to: 

  • Prepare material samples for microscopic examination 
  • Use a microscope for glass observation 
  • Be able to identify the structure and composition of glass with microscopy 

How To Observe Obsidian 

As we mentioned before, obsidian is a natural substance that is formed from volcanic activities. 

In most cases, the stone is formed when molten rocks cool at a rapid pace, which causes the atoms to cement into a non-crystalline structure.

Despite its notable appearance, the gemstone can vary in color depending on its place of formation, with certain specimens being brown and covered in white spots. 

What You Will Need

  • Obsidian sample 
  • Microscope glass slides 
  • Coverslips 
  • Plastic container 
  • Canada balsam or resin 
  • Grinding wheel 
  • Continuous-rim blade 
  • Water 

Instructions 

To examine the obsidian sample, you will need to prepare the material for observation, which requires you to cut the stone into thin sections that can be viewed and studied under the microscope. 

This process can be executed with the following steps: 

  1. To start, you will need to hydrate the obsidian sample by placing it in a container filled with cold water. 
  1. Once the obsidian has moistened, you can use a continuous-rim blade to slice the stone into smaller pieces between 0.5 and 1mm thick. 
  1. Following this, you will need to use a grinding wheel to remove any edges or material that has formed around the sample. 
  1. Once the edges have been removed, you can take a small sample of balsam or resin and use it to fuse the sample to a clean glass slide. 
  1. If you need to reduce the thickness of the stone further, it is possible to do this using a rotating metal lap with about 10 micron-sized abrasives. This should reduce the stone to about half of its original size. 
  1. Following this, you will need to remove the obsidian from the slide and use the resin to cement the other side – this means that the grounded surface will now be fused to the glass. 
  1. Once the sample has been secured, it will need to be grounded again until it reaches a thickness of 0.08mm. However, it’s also possible to keep working the obsidian until it becomes transparent. 
  1. Use the Canada balsam or resin to cover the sample with a coverslip so that the stone is sandwiched between the slide and the coverslip. 
  1. Following this, the sample can be mounted on the microscope stage, where it will be available for observations. 

Now that you understand how to observe a material like obsidian, it’s time we took a detailed look at how to observe a more common kind of glass. 

How To Observe Windscreen & Common Glass 

When it comes to windscreen and common glass, both materials will often undergo serious examinations to determine their composition and durability. 

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Because of this, different techniques are used to analyze the substance, with one of the most common involving the use of a microscope. 

What You Will Need

  • Glass sample (either common or windscreen) 
  • Colored paper
  • Stereo microscope
  • Pair of lab tweezers
  • Glass slide 

Instructions 

To start, you will need to use a pair of lab tweezers to select a small piece or shard of the glass before placing it on a slide or piece of paper. For the best results, we would advise using a piece of colored paper to achieve a clear observation. 

While it is possible to use a stereo microscope to complete this procedure, you can also use a macroscope.

In comparison to stereo microscopes, macroscopes can provide a much grander field of view, which means they also come with long working distances.

However, stereo microscopes are able to provide a true stereo image, which can make the observation easier. 

How To Mount Glass Samples On A Microscope 

During this process, it’s important to remember that the obsidian sample will also need to be observed using a compound microscope. 

Instructions 

  1. To start, you will need to turn the stage adjustment knob and lower the stage, as this will make it easier to mount the material sample. 
  1. Once you have lowered the microscope stage, you can place the slide onto the stage and secure it in place with the included stage clips. 
  1. Following this, you can turn the revolving turret and set the microscope at the lowest power objective in place. 
  1. When the objective has been set, you can raise the stage using the stage adjustment knob and secure it in the best position. 
  1. Once the stage has been secured, you will need to turn the course and adjustment knobs until the image comes back into focus. 
  1. It is also possible to adjust the amount of light by turning the condenser – because of this, you will be able to set the correct intensity, which will ensure a clear image and focus on the sample. 
  1. Following this, you will also need to lower the stage and turn the turret to switch on the magnification, which will allow you to observe the slide. This will make it easier to compare the slide to a high and low magnification. 
  1. Once you have finished the observation, you can lower the stage and remove the slide from the microscope. 

What Is The Observation? 

When a material like obsidian is viewed under a microscope, the stone will often appear black with some hydration around the rims, which could be the result of glacial abrasion.

In contrast, windscreen or common glass (under x6 and x60) will show a clean fracture surface with few scratches and abrasions. 

Of course, the final result can vary on the material and where it came from, as some slides could demonstrate pits and scars, which will cover the surface of the glass.

If you want to enhance this image, it’s possible to use a macroscope (around x100 and x120) to get a better look at the scratches and marks. 

While we would recommend using a stereo microscope or a macroscope to observe the material, students can also compare different forms of glass with the use of fluorescence and polarized microscopes. 

Why Is Glass Studied? 

Since its invention, glass has confused and frustrated scientists, as the material cannot be truly defined as a solid or liquid. 

Because of this, many scientists and researchers have dedicated their lives to the study of glass and its composition. For instance, if we were to examine a glass of wine, we would see that the molecules in the wine are close but not fixed in position.

This is because wine is a liquid and features a different molecular structure than solid items. 

However, if we were to examine the glass, we would also see a similar pattern, although the molecules would not be free to move around.

On an atomic level, the two materials look the same, which means they are similar despite their outward appearance. 

Despite their centuries of research, scientists still have no idea what prevents certain liquids from cementing themselves into glass, which is one reason why the material continues to frustrate those in scientific circles. 

Final Thoughts 

As we mentioned earlier, there are various kinds of glass used for different purposes, from decorative pieces and protection to windows and doors.

It is possible to use a compound, stereo, and macroscope to observe and compare these different materials, which should demonstrate the contrasts in their structure. 

For this experiment, you can use any materials that you want, whether that be raw obsidian, common crystal, or windscreen composite. Once you compare how these materials appear, you will be able to learn more about their compositions. 

While it remains impossible to observe the components of glass under a microscope, you can still examine the surface to learn more about the material and its creation.

Not only can this reveal the materials used to make the glass, but it can also determine its place of origin, molecular composition, and authenticity.

Jennifer Dawkins

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