From magnifying glasses to tinted windows to one-way mirrors, people prize glass for its ability to transmit (or not transmit) light.
Measuring light transmission and transmittance plays a huge role in selecting an appropriate type of glass for your needs. Transmittance measures the amount of light able to pass through a material without the material reflecting or absorbing it. Therefore, transparent glass will transmit 100% of light, translucent material only allows some light to come through, and opaque glass will achieve close to 0% transmittance.
A few key differences exist between light transmission and transmittance. Understanding the distinction between these two terms will help you select the perfect type of glass for your application.
Transmission vs. Transmittance
Transmission refers to the amount of incident light that successfully passes through glass or other material, and it’s usually expressed as a percentage of light that made it through the material. On the other hand, transmittance refers to the amount of light that a material disperses, effectively resulting in an inverse value of that found for transmission.
There are two basic types of transmission—external and internal—and both differ from light transmittance:
External transmission is calculated from the intensity of the incident light as it enters the glass versus the light’s intensity after exiting the glass. This transmission measurement technique provides an accurate figure of the actual amount of light allowed to pass through a material.
Internal transmission is determined by the light’s intensity once it has entered the glass versus its intensity after it leaves the glass. Internal transmission primarily measures the light filtration ability of the glass itself, allowing you to get a more accurate idea of the glass’s properties.
Transmittance refers to the amount of light energy that the glass absorbs, scatters, or reflects. It’s measured using the formula T = I/I0, with T denoting the transmission intensity, I indicating intensity, and I0 indicating intensity at the start. This calculation allows you to determine the ratio of transmitted radiant power to incident radiant power, giving a greater idea of a glass’s ability to block photons.
How Does Transmittance Apply to My Application?
Transmittance values can vary based on which application or common industry nomenclature they use.
For example, while most manufacturers measure industrial glasses in terms of external transmittance, they usually measure filter glasses in internal transmittance. This is because manufacturers can put an anti-reflective (AR) coating on the glass’s surface, reducing the amount of light intensity lost to reflection.
A couple of common applications that measure transmission include:
Testing window tint or films for cars, homes, and businesses. Desired tint levels will correspond with the amount of light the glass transmits.
Measuring glass clarity. Many industries have stringent specifications governing the use of glass in assembly regarding both external or internal transmission. For instance, FAA specifications for airport and aerospace applications typically govern the product’s external transmission potential.
It’s also good to keep in mind that engineers who design optics for extreme environments must recognize that each type of glass will have slight variations in chemical, thermal, and mechanical properties, all of which factor into their ability to reflect and absorb light.
Glass for All Occasions at Swift Glass
At Swift Glass, we pride ourselves on having delivered industry-leading custom glass manufacturing services for almost 100 years to OEMs across the country. Our experience and dedication to customer success enables us to understand our customers’ intricate needs and exceed their expectations.
We’re an ITAR-registered, ISO 9001:2015–certified company and a worldwide leader in fabricated glass parts. We offer holistic assistance in glass crafting, material selection, and custom design, maintaining a high standard of precision and quality.
To learn more about the optical properties of glass, download our latest eBook here, and don’t hesitate to contact us today if you have any questions.
Understanding the behavior of light can be an important factor when determining which glass materials to use for your manufacturing process. When light passes through a substance, it decreases in velocity. This is manifested by an increase in the substance’s refractive index. Much can be learned about the optical properties of a glass material by looking at its refractive index.
Refractive index is useful for various reasons. For one thing, it can be used to calculate the focusing power of lenses and the dispersive power of prisms. It can also be used in estimating the thermophysical properties of hydrocarbons and petroleum mixtures.
What is the Refractive Index?
Also commonly referred to as the index of refraction, the refractive index, n, measures a ray of light as it travels from one medium to another. As it begins to travel through a material, the interaction between electrons and photons reduces the speed of light. As the density of the electrons increase, the velocity of light becomes slower. This is why light moves at its highest possible speed in a vacuum, where no electrons hamper its speed.
Knowing the refractive index – among other thermal, chemical and physical properties – helps ensure that the glass material you’re considering for your application is suitable for its intended use.
Determining the Refractive Index of a Material
The ratio between the speed of light in a vacuum and the lower velocity of the light as it travels through a given material enables us to determine the refractive index of a given material.
In addition, the amounts of transmitted and reflected light will determine not only the refractive index of a glass material, but also its angle of refraction. This is because light gets transmitted and reflected as light rays pass through the surface of a glass material.
The light’s transmission angle can be calculated using Snell’s law:
The discrepancy between the light’s transmission and the incidence angle becomes bigger as the index of refraction becomes larger. When this occurs, there is a change in the existing refractive index between the glass and the surrounding medium.
When Θi = 0°, the amount of reflected light can be determined using the following formula:
Lastly, the intensity of light is reduced by an average of 4% due to lost reflection from the surface of most glass materials with a 1.5 refractive index.
A change in the index of refraction due to changes in wavelength is known as chromatic dispersion.
Swift Glass has been providing custom glass manufacturing services for nearly a century, and providing high-quality solutions to OEMs is one of our core principles. Our experience and dedication to customer service enables us to understand the intricate needs of our customers, and to exceed their basic needs.
An ITAR registered, ISO 9001:2015 certified company, Swift Glass is a privately-owned global leader in the quality fabricated glass parts. Swift Glass offers assistance in craftsmanship, material selection, and manufacturing of custom solutions, and design, while guaranteeing high quality and precision.
Material Options to Substitute for Corning® Vycor® Glass
Invented by Corning in 1939, Corning® Vycor® Glass has been used in a wide range of applications over the years, from laboratory equipment to early spacecraft viewing ports.
A blend of 96% silica and 4% boron trioxide, Corning® Vycor® Glass is a high-temperature glass valued for its low coefficient of thermal expansion — 7.5 x 10-7/°C when measured between 0 °C (32 °F) and 300 °C (572 °F). It also features excellent thermal shock resistance and superior optical qualities.
Recently, however, Corning discontinued Corning® Vycor® Glass, and now companies across various industries are searching for reliable alternatives.
Quartz: A Viable Corning® Vycor® Glass Replacement
Among dozens of types of glass, quartz is one of the best replacements for Corning® Vycor® Glass. Extremely versatile, quartz — like Corning® Vycor® Glass — is a high-silica glass, as it’s produced from naturally occurring quartz, which is composed entirely of silica dioxide. Because quartz is naturally occurring, quartz glass may have residual levels of impurities, but these typically only affect ultraviolet transmission.
Versatile and reliable, quartz is an ideal Corning® Vycor® Glass replacement for any project that requires strong, high-performance glass.
Although quartz is an excellent Corning® Vycor® Glass alternative for many applications, you may require a different material depending on the intended end use of the glass. Extreme applications, in particular, often necessitate a different Corning® Vycor® Glass substitute.
Founded nearly 100 years ago, Swift Glass Co. is an industry-leading manufacturer of fabricated glass parts. Over the decades, we’ve developed a wealth of expertise working with a variety of glasses, many of which are well suited for use as Corning® Vycor® Glass alternatives.
Used in a range of industries and applications, sight glass is used to check the level of liquid in a reservoir or supply line. Critical tools for ensuring operations are running safely and smoothly, these transparent tubes or windows allow users unimpeded observation in order to monitor conditions in piping, vessels, chemical reactors, and other industrial equipment.
Because sight glass is made from sturdy glass substrates, it can be used in harsh conditions and can withstand high temperatures and pressures, as well as chemical attacks. Sight glass may be subjected to thermal shock, caustics, abrasives, and impacts. But only properly designed, appropriately thick sight glasses will offer reliable resilience.
Specific sight glass design will depend on the specific application, so it’s important to carefully consider the exact conditions the glass will be exposed to and any potential hazards or special requirements. Various internal and external forces can impact the strength of glass components, and even minute flaws in the glass can lead to failure, so selecting the appropriate thickness is crucial.
Glossing over these preliminary considerations can result in a subpar design, increasing the risk of sight glass failure. This wastes both time and money, as projects must be stopped until the equipment can be repaired or replaced. Even more importantly, these failures can be extremely dangerous to the operator and surrounding workers, resulting in injury or even death.
There are several factors to consider when selecting sight glass thickness, but temperature and pressure, in particular, play key roles.
When designing sight glass, it’s important to consider any temperature extremes in which it will operate, determine whether the temperature will fluctuate, and pinpoint the highest and lowest possible temperatures. Certain glass types perform differently depending on the temperature range. For example, soda lime glass can be used at temperatures less than 300 °F, while borosilicate glass can be used at temperatures up to 500 °F. Quartz or sapphire glass should be used for temperatures greater than 500 °F.
Pressure can also fluctuate greatly during operations, but it’s first important to understand that pressure is classified in multiple types: Working pressure is the greatest pressure allowable in an operating environment; design pressure is the maximum pressure the specific system has been designed to withstand; test pressure is generally specified by end users in order to ensure that components not just meet but exceed safety requirements; and burst pressureis essentially what it sounds like — the amount of pressure that can be applied before failure. (Burst pressure tests are usually only conducted in highly sensitive or critical applications, such as nuclear facilities.)
The various pressure capabilities of sight glass assemblies are determined by the material, thickness, and unsupported diameter, and both normal operating pressure and peak upset pressure should be taken into consideration when creating sight glass thickness specifications.
Find the Glass Thickness You Need
As a worldwide leader in the manufacture of quality fabricated glass parts, Swift Glass has years of experience fabricating sight glass for many applications. To make the process for our customers even easier, we’ve created a glass-thickness calculator; simply type in the unsupported diameter of the glass you’re working with, as well as the PSI it needs to withstand, and it will provide the recommended thickness to ensure optimal strength and durability. If you already have the unsupported diameter and the thickness of the piece of glass you’re working with — enter those values and calculate the PSI it will be able to withstand.
The strength of any 3D printed object depends on the quality of its base, the very first layer of deposited substrate. Even the most well-engineered part risks malfunction if there are variations or flaws in the printing surface. To ensure optimal part quality and performance, it’s critical to select a reliable 3D printing bed.
A range of 3D printing surface materials are available — everything from acrylic plastic and aluminum, more traditional surfaces, to specialty materials such as thermoplastic polyurethane. In recent years, though, glass has become a go-to choice.
Borosilicate glass, in particular, is extremely well-suited for 3D printing processes in a range of applications. Below, we’ve outlined three of its main advantages.
Physical Strength and Thermal Fatigue Resistance
A blend of silica and boron trioxide, borosilicate glass is highly durable.
3D printing requires high amounts of heat — both from the molten printing material and, if needed, a heating bed — but borosilicate features a very low coefficient of thermal expansion, meaning that any physical changes it undergoes when subjected to high temperatures are minimal. This low coefficient of thermal expansion prevents the glass from warping during use, which, in turn, prevents printed objects from adopting flaws in their base layers.
Due to its method of manufacture, borosilicate glass also features a flatter surface than traditional 3D printing bed materials. Its unique physical chemistry allows printing beds to resist the crowning and warping that often occur with materials like aluminum.
Not only is it annoying to have to constantly adjust printing beds or printer settings in order to maintain a flat surface, it’s also a waste of time. And ultimately, constantly adjusting systems and settings can result in faulty prints. Borosilicate glass printing surfaces provide consistent flatness, eliminating the need for adjustments.
Minimal Part Warpage and Easy Removal
When used in conjunction with a heating bed, borosilicate glass 3D printing beds minimize or eliminate warpage in completed parts. Glass beds conduct heat evenly, which allows the printed part to cool evenly in a controlled manner, thereby reducing the risk of warpage.
Borosilicate glass’s low coefficient of thermal expansion also aids in the removal of completed and cooled parts from the surface. Borosilicate glass expands minimally when heated, so it does contracts minimally when cooling. Parts contract during cooling at a higher rate relative to the glass bed, allowing them to naturally pop off the glass, making removal easy and force-free, no tools required.
One of the most versatile 3D printing bed materials available today, borosilicate glass offers a range of benefits over more traditional options such as aluminum and ceramic.
To learn more about the benefits of borosilicate glass in 3D printing applications, check out our 3D printing portfolio or contact the team at Swift Glass today.
Glass materials can receive many different types of glass edge treatments, each of which will uniquely affect the overall functionality and performance of the finished piece. Edging can improve safety, aesthetics, functionality, and cleanliness while improving dimensional tolerance and helping to prevent chipping.
Below, we’ll explore five common glass edge types and their unique benefits.
Cut and Swipe or Seamed Edges
Also referred to as safety seams or swiped edges, this type of glass edging — in which a sanding belt is used to lightly sand off sharp edges — is primarily employed to ensure the finished piece is safe for handling. This style of edging does not provide a smooth, cosmetically finished edge and is not used for decorative purposes; therefore, this method is ideal for applications in which the edge of the glass piece will not be exposed, such as the glass installed into the frame of fireplace doors.
Grind and Chamfer (Bevel)
This type of edging involves flat grinding glass edges until they are smooth and then running the top and bottom edges along a belt to eliminate sharpness and remove chips. The resulting glass piece features a smooth chamfer top and bottom with an exterior ground edge. Available with straight or curved bevels, chamfered edges are most often seen on frameless mirrors, such as those on medicine cabinets.
Pencil grinding, achieved through the use of a diamond-embedded grinding wheel, is used to create a slightly rounded edge and allows for a frosty, satin, or matte glass finish. “Pencil” refers to the edge radius, which is similar to a pencil or C shape. This grind is also referred to as a Semi-Polished Edge.
Pencil polished glass edges are ground smooth, finished with a shiny or glossy polish, and feature a slight curve. The unique finish makes pencil polishing ideal for aesthetics-focused applications. Like pencil-ground edges, the edge’s radius is similar to a pencil or C shape.
This method involves cutting the edges of the glass and then flat polishing them, resulting in a sleek appearance and shiny or glossy finish. Most flat-polished applications also employ a small 45° angle chamfer on the top and bottom glass edges to remove sharpness and “chatter” which can also be polished.
Swift Glass can accommodate a variety of glass edgework methods. To learn more about the different types of edgework available, download our comprehensive Edgework Terminology Infographic, complete with multiple surface views and detailed descriptions of various glass edge types.
If you’ve ever wondered why your glass order was quoted at a certain number, you are not alone.
“What makes up the cost of my glass?” is one of the most common questions we get here at Swift Glass.
There are a variety of factors that contribute to the price of a glass part — the quantity of the order and the size of your glass piece being the two most obvious factors. Here are three other notable considerations.
Advances in manufacturing technology have led to advances in glass shaping capabilities. Processes like state-of-the-art glass drilling, waterjet cutting, and computer numerical control (CNC) machining can all be applied to glass shaping.
Today, glass parts can have virtually any shape, from standards like squares and circles to highly complex organic, irregular, and geometrical shapes. The more complex the shape of your glass, however, the more advanced technologies required to produce it. The use of advanced machining processes adds to your glass prices.
There are many different forms of edgework that you could specify for your glass part, and they all have an impact on the price of glass.
The most basic edgework, a simple cut, is required for virtually every glass part as a matter of course, and will have minimal to no impact on the cost of glass.
Cut and swipe, a swipe being a very slight bevel, will increase your glass price modestly. Very complex edge grinding, such as special or custom bevels, could increase the cost of glass considerably.
Strengthening & Tempering
Strengthening and tempering procedures — additional steps performed after your parts are cut — increase your glass prices. If your glass parts are going to be used in a challenging environment and face exposure to extreme heat, pressure, stresses, or chemicals, a strengthening processes is likely required.
Chemical strengthening processes are best for glass that will encounter wind load and thermal stress, while thermal tempering is ideal for glass that will be used in high pressure, high heat, and explosive environments.
Get More Price Factors
The glass price factors here are only a small sample — there are dozens of considerations that go into the price of a glass quote. To learn more about the different ways glass cost is determined, download Swift Glass’s latest guide, What Affects the Price of My Glass?
Glass plays an essential role in medical equipment — especially inside X-ray detectors.
These medical devices require a specialized glass composition to ensure the material withstands extreme heat and energy, as well as repeated applications of radiation technology.
In addition to high levels of heat and light, the glass in X-ray equipment must also offer the following properties:
Endurance to high transition temperatures.
Low thermal expansion to maintain dimensions under the stress of construction and operation.
Pristine surface quality and flatness for the best quality images and highest accuracy.
BOROFLOAT® Glass: An Excellent Choice for Medical Applications
Of the many glass options available for medical devices, BOROFLOAT® glass is one of the best choices. While general glass absorbs radiation and deteriorates, BOROFLOAT® glass is not easily changed by high-energy radiation, and is therefore not as susceptible to darkening, as seen in the photo below.
BOROFLOAT® glass is also extremely versatile, and can serve as a scintillator substrate, cover slip, protective window for X-ray rooms, and many other related applications.
3D printing, also called additive manufacturing, is rapidly transforming industrial manufacturing as we know it.
Initially used to create models and prototypes, 3D printing is now increasingly being used to construct finished products.
In the near future, this technology will hold the power to manufacture food, cars, implants, and even soft tissue organs.
The 3D printing process uses computer-automated layering of material to create a three-dimensional object. Just about any material available in liquid or powder form can be 3D printed. The industrial robots performing the layering can be programmed with complex shapes and geometries to produce a diverse range of parts with extreme precision and detail.
Where Does Glass Fit In?
During the 3D printing process, the object being created requires a platform on which to rest. Because of the high temperatures experienced during 3D printing, this plate must be made from durable, heat-resistant materials.
Borosilicate – a glass substance constituted of silica and boron oxide – is the material of choice for these applications. An extremely low coefficient of thermal expansion makes borosilicate more resistant to thermal shock than any other common glass. Even when exposed to high temperatures (up to 500°F or 260° C), borosilicate remains durable and clear without losing functionality.
Get More Information from Swift Glass
Swift Glass has been a worldwide leader in custom glass fabrication for almost 100 years. In addition to waterjet cutting, glass tempering, polishing, grinding, lapping, and drilling services, we offer a variety of borosilicate and infrared reflecting borosilicate (IRR) glass from major manufacturers such as Corning and Schott.