Some Like It Dot: Car Windshield Markings Explained

If you’ve ever been sitting in Tucson traffic, bored out of your mind, you may have noticed the solid black band and all those little dots around the fringes of your windshield. You may have even wondered what those windshield markings are for. 

You’re not the only one. Jalopnik’s David Tracy thought the same thing, so he did some digging and found what we in the auto glass industry already knew: they’re more than just decoration.

In this article, we’ll break down what exactly the different windshield markings mean. As with many things involving your vehicle, the more you know about the glass, the better off you are!

What Is the Black Band Around the Edge? What’s It For?

When you look along the edge of the windshield, you’ll notice a band of solid black. It actually serves many more important purposes than you may think.

That black band that runs around the entire edge of the glass is called the “frit.” It is a baked-in ceramic paint that’s essentially impossible to scrape off. That frit band, which is a permanent part of the windshield, performs a number of very important jobs: 

Prevents Damage to the Sealant/Adhesive From UV Rays

Possibly most importantly (especially here in Tucson), the outward-facing side of the frit acts as a shield and helps to dissipate UV rays from causing deterioration to the urethane sealant that holds the windshield in place. Without this added protection from constant exposure to direct sunlight, the adhesive bond of the sealant would become weakened. This sealant is vital because it both holds the glass in place and seals the unit to prevent rain/debris from entering the cabin.

Creates a Rougher Surface for the Window Adhesive To Stick To

In the past, vehicle manufacturers used gaskets to create a seal around the windshield and prevent water from getting inside the vehicle. Then, over the top of that gasket, a chrome trim would be fastened to hold the windshield in place and prevent it from rattling out. It was in the 1950s and ‘60s that vehicle manufacturers shifted from using metal trim to using adhesives to hold the glass in place. When this happened, it was necessary to have a way to ensure good adhesion and protect the glue. This was when the black frit band became standard on essentially all vehicle windshields.

The inside-facing side of the black frit band also serves an important purpose. It provides a rougher surface for the adhesive sealant to stick to since this part of the windshield is the contact point between the glass and the vehicle’s frame. This helps ensure that the adhesive can form a strong bond all the way around the windshield to properly hold it in place.

Helps Improve the Appearance of the Windshield

While serving a functional purpose, the inside-facing side of the frit band also serves a cosmetic function. It creates a visual barrier and prevents any adhesive along the frame of the windshield from being visible from the outside. This helps provide a more “polished” appearance.

The Dots Coming off the Solid Black Frit

Along with this solid black frit around the edge of the windshield glass, you’ll also see black dots, sometimes referred to as a “dot-matrix.” Technically, these dots are part of the frit and form a halftone pattern. This creates a smooth gradient, with the dots decreasing in size as you move inwards from the solid black band toward the center of the glass. 

As frits have been evolving over the years, there are now different variations in how these dots may appear. Of course, the most common pattern you’ll see consists of round dots. But sometimes, they’ll also be arranged in a teardrop shape or angular form. Some vehicle manufacturers have even started including their logo or small graphic images in the pattern, like the silhouette of a Jeep. 

But regardless of their exact pattern, these intriguing black dots are extremely underrated for the purposes they serve, and not many people consider why they’re there.

One of the purposes they serve is providing a more visually appealing look by providing a smoother transition from the solid black frit to the clear glass. But the dots also serve an important functional purpose. 

During the manufacturing of windshields, the glass is bent in a large, hot oven to create the shape needed to fit into a vehicle’s frame. Because the solid frit band is black, it heats up faster than the transparent glass does. This is also true when the vehicle is out in direct sunlight. Without the gradient dots, there would be a sharp difference in thermal temperature between the black band and the clear glass. This would cause an optical distortion known as “lensing” where straight lines would look curved or bowed inwards toward the center.

So, the gradient dots are used to help dissipate heat and spread it out more evenly, thus minimizing any distortion and hiding it from view.

On many modern cars, there’s now another group of dots on the windshield, sometimes referred to as “third-visor frits.” These are located on the windshield behind the rearview mirror. This set of dots works to help block the sun from shining between the front sun visors.

Decoding the Stamp of Letters and Numbers on the Glass

When looking at your windshield, you may have also noticed a stamp with a variety of letters, numbers, and symbols. This stamp, which is usually found in one of the bottom corners of the windshield, is actually referred to by those in the auto glass industry as a “bug.” This bug provides both drivers and glass technicians with pertinent information about the windshield that may be needed when looking up the windshield’s part number.

If you need to have your windshield replaced, it can be helpful to provide the auto glass shop with the information found in the bug. Knowing exactly what is included in the bug and how to decode the information can also help you confirm that your new windshield is quality glass.

A windshield’s bug contains a lot of different bits of information. Some of the things that are often found in the stamp include:

  • Vehicle manufacturer—In many cases, if the windshield is the original factory part or an original equipment manufacturer (OEM) replacement, it will have the vehicle manufacturer’s company logo at the top of the bug.
  • Auto glass manufacturer—Another logo that you’ll usually find near the top of the bug (often just below the vehicle manufacturer’s logo) is the auto glass manufacturer. It is not often the case that windshields are made directly by the vehicle manufacturer. For example, you may see the Nissan logo with the Vitro company logo below it. Vitro is one of the auto glass manufacturers that is contracted by vehicle manufacturers.
  • Date of Manufacture—Sometimes, the bug will also contain the month and year that the windshield was manufactured.
  • Type/model name of the auto glass—Usually, below the logos, you’ll find the specific type of auto glass that makes up the windshield. “Temperlite,” “Therlite,” and “Tempered” all indicate that the windshield is a type of tempered glass, while “Laminated” or “Lamisafe” indicates that it is a laminated auto glass. You may also see “Tintex,” which means it is a type of slightly tinted glass.
  • Expanded indicator of the type of glass—To the side of the main indicator of the type of glass, you may also see a Roman numeral in italics. This is a further indicator of the subtype of auto glass. For example, “I” indicates that it is an extra durable, hardened windshield, “II” means that it is a multilayer conventional windshield, while “III” means it is a treated multilayer wind-rated windshield.
  • Declaration of passing safety tests—Within the bug, you may also see the words “LAMINATED AS1.” There are several different types of glass, including AS1, AS2, and AS3. In the U.S., federal regulations require glass to pass specific safety tests regarding impact and light transmission to be used in vehicles. 

AS1 glass passes all of these tests and is the clearest form of glass, while AS2 glass does not pass the impact tests. AS3 glass is a darker tint and is referred to as privacy glass since it does not permit more than 70% of incoming light to pass through. AS3 glass is most commonly used in back side windows and the rear windshield in vehicles. AS1 glass is the only type that passes all safety tests, so it is the only glass authorized for windshield use.

  • Additional countries where the glass is distributed and meets safety specs—Near the “AS1” in the bug, you may see a letter within a circle. For example, an “E” inside of a circle means that the windshield is also distributed in Europe. If it says “E1,” that would indicate it is specifically distributed in Germany. Each European country has a number associated with it. A “CCC” means that it is also distributed in China. 

These countries also have safety regulations/ratings, similar to the AS1 safety rating in the U.S. So, for example, you may see a long number next to the circle with an “E” in it. Let’s say it is “43R-000499.” The “43R” means that the windshield conforms to the European standard of safety regulation #43. The “000499” that follows indicates the approval number assigned to the windshield.

  • Federal Department of Transportation (DOT) number—Not all windshields will have company logos included in the bug. But all of them will at least list the DOT number that the glass company is registered under.
  • Manufacturer’s part number—Usually, to the right of the DOT number will be the manufacturer’s part number that allows them to identify the glass. For example, you may see something like “M119.”
  • Country the glass was manufactured in—Towards the bottom of the bug, it may include where the glass was made. For example, one of the main manufacturing centers for the glass company Vitro is in Mexico. So, the bug would say, “Hecho en Mexico.” 

Additional Things Sometimes Included in the “Bug”

There may also be additional codes or symbols within the bug that are added by the manufacturer to indicate information such as added features, etc. Some of these may include:

  • VIN of the vehicle—Sometimes, the vehicle’s identification number will be found below the windshield’s bug. This number will be the same as what is on the engine and the body of the vehicle. When it’s on the windshield, the VIN will usually appear either in the form of black dots or etched directly into the glass. It may be the full number, or sometimes it is just the last few numbers.
  • Circle with the letters “iR” inside of it—This symbol indicates that this windshield is made of chameleon athermal glass, which usually also has a slight purple hue to it. With this glass, in addition to the polyvinyl butyral film between the two layers of glass, there is also a layer of transparent silver film. This film reflects and dissipates 70-75% of heat from direct sunlight.
  • Thermometer icon—This symbol is used to indicate that the athermal glass has a sun-reflective coating added to it. If the symbol also has the letters “UU,” the windshield has an ultraviolet filter as well.
  • Double-sided arrow—Athermal glass that has an anti-reflective coating will have this symbol included in the bug as well.
  • Ear-shaped icon—This symbol indicates that the glass has a noise absorption feature added to it.
  • Raindrops icon—A windshield with a symbol of water drops means it has a water-repellent effect that has been added to it.
  • Hammer icon—This symbol is used to indicate a windshield that has an increased impact resistance feature.

An additional feature that may be included on the windshield is what is known as top-tinting. While this won’t be indicated in the windshield’s bug, it will be hard to miss it. Top-tinted windshields have a darkened strip across the top of them, usually extending 3-4 inches from the edge of the glass, which helps block some of the bright sunlight that may shine into the glass.

You Can Count on the Local Experts in Auto Glass in Tucson—Max Auto Glass

Now you have an idea of what the markings and dots on your windshield are for. Even though you probably have not spent too much time pondering their purpose, having this knowledge can prove helpful in some situations, especially if you find yourself needing to have your windshield replaced.

The experienced technicians at Max Auto Glass are trained professionals who understand the many functions and necessities of your windshield’s frit, bug, and much more. 

So, when you need auto glass repair in the Tucson area, whether you need someone to repair the windshield or replace a side window, you can count on the experts at Max Auto Glass

Windshield Marking FAQs

Are there different grades of windshields?

Yes! Not all windshields are the same in terms of specifications and quality. When you need windshield replacement, it is important to know the difference between the different types of windshield auto glass. There are three main types of windshields. 

Dealer Auto Glass

A dealer windshield is the branded replacement for the vehicle’s original windshield that came with the vehicle off of the assembly line. This means it will fit the manufacturer’s specifications and have the vehicle manufacturer’s branding on the glass. This is because it is coming directly from the company the vehicle manufacturer contracted with for the windshields.

This is especially important for people who are restoring or preserving a vehicle. But dealer windshields usually come at a premium price.

Original Equipment Manufacturer Auto Glass

Often mistakenly thought to be the same, Original Equipment Manufacturer (OEM) glass is very similar to dealer glass. This type of windshield is made to the exact same specifications as the original vehicle design but is not necessarily manufactured by the same company that originally made the windshield that came in the vehicle.

These windshields will not usually have the vehicle brand on them but, besides that, are indistinguishable from dealer glass in terms of quality, material composition, thickness, color, shape, and fit. Usually, an OEM windshield will be cheaper than a dealer glass windshield but more expensive than an aftermarket windshield. Prices for OEM windshields will usually run 40% to 60% higher than a comparable aftermarket option.

Aftermarket Auto Glass

In terms of cost, aftermarket windshields are the cheapest choice. But there are some important things to consider with these windshields. Aftermarket auto glass is usually manufactured to all mandatory safety regulations, but the exact design specifications will not match the original equipment windshield that came in the car due to copyright laws.

This means that an aftermarket windshield will do its job, but the exact thickness, composition, durability, etc., may be slightly different from the original windshield design. In some cases, advanced driver assistance systems (ADAS) attached to the windshield will not work with replacement aftermarket windshields. But, depending on your vehicle, this glass can be a great choice if you are working with a tight budget.

When trying to decide the right choice for your windshield replacement, here at Max Auto Glass, our team of auto glass experts in Tucson can help you decide which type of windshield may be the best for you and your vehicle.

Where is the part number on a windshield?

Windshields don’t always have a single, universal part number to identify them like other vehicle parts often do. This is because different windshields from different auto glass manufacturers will all have the same sizing specifications to fit one particular vehicle.

But on every windshield, a stamp of letters, numbers, and symbols provides the technicians at an auto glass shop with all pertinent information about the windshield, including manufacturer, type, etc. Usually found in one of the bottom corners, this stamp is technically referred to as the windshield’s “bug.”

In the bug on your windshield, you may see a manufacturer part number to the right of the DOT symbol, for example, “M119.” This number identifies that particular type of windshield specifically from that glass manufacturer.

How do I know which features my windshield has?

Your car’s windshield can have a variety of different features built into it. The identification stamp (or “bug”), which is usually at one of the lower corners of the glass, includes manufacturer codes that help identify some of these features. For example, the word “Tintex” indicates that the type of glass is a special, slightly tinted glass. You may also see an italicized Roman numeral to the right of the main glass type indicator. For example, “I” indicates that the glass is a hardened, extra durable windshield. 

You will also be able to notice some common windshield features just by looking at the glass. For example, many newer-model vehicles have a shade band across the entire top of the windshield that helps keep the sun out of the driver’s eyes. This semi-translucent blue or green band is easily noticeable when looking at the glass. 

If you need to replace your windshield, our expert technicians can decipher the information included in the bug and from the manufacturer. We can ensure you get a high-quality replacement windshield with all the same features you had.

How do I know if my windshield has a rain sensor?

There are a couple of easy ways to determine if your vehicle has a rain sensor system integrated with your windshield that will turn on the windshield wipers when rain is detected on the glass.

  • Do your wipers automatically start when it’s raining?
  • Is there a small square sensor mounted on the windshield near or behind the rearview mirror?

Looking at your windshield from the outside, the rain sensor is usually a lens or strip of film that faces outside and is located between the back of the rearview mirror and the glass.

Some vehicles have both a rain sensor and a light sensor, with these two sensors being adjacent to each other.

What is auto glass calibration?

Windshield ADAS calibration is the process of returning the ADAS that are integrated with the windshield back to the precise manufacturer specifications. These systems control things such as your automatic windshield wipers, collision avoidance systems, and lane departure systems.

During the calibration process, the technician will adjust and test all the cameras and sensors on the windshield to ensure these ADAS are still working properly. Your ADAS should always be recalibrated after replacing your windshield. Not doing so can mean these features may not work correctly and could lead to an accident.

The experts at Max Auto Glass are experienced in more than just windshield replacement, car window repair, and power window repair—we can also ensure your windshield ADAS is properly recalibrated.

The Max Auto glass Difference

  • High-Quality Products
  • Technicians Certified By The Auto Glass Safety Council™
  • Excellent Customer Service
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