Identifying Flat Glass Types

Glass Types

When it comes to installing window tint on architectural or flat glass, understanding the type of glass you're working with is crucial. Different glass types have different properties that can affect the performance and safety of window films. At Flexfilm, we use a film-to-glass compatibility chart to help customers determine which films are suitable for their windows. However, the terminology can sometimes be confusing. This guide aims to clarify the various glass types and what they mean.

1. Single Pane Glass

• Definition: Single pane glass consists of one layer of glass. It’s the most basic and traditional type of window glass.
• Considerations: Single pane windows are less energy-efficient and offer minimal insulation compared to dual or triple pane glass. However, they are generally compatible with a wide range of window films.

2. Dual Pane (Double Pane) Glass

• Definition: Dual pane glass consists of two layers of glass separated by a space filled with air or gas (often argon) to improve insulation.
• Considerations: Dual pane windows are more energy-efficient and help reduce heat transfer. When applying window film to dual pane glass, it’s important to consider the film’s impact on thermal stress, as improperly selected films can cause the glass to crack.

3. Triple Pane Glass

• Definition: Triple pane glass features three layers of glass with spaces in between, typically filled with gas, for enhanced insulation.
• Considerations: Triple pane windows provide superior insulation and energy efficiency. However, due to their thickness and the added layers, careful selection of window film is necessary to avoid issues like excessive heat build-up.

4. Low E Glass

• Definition: Low E (Low Emissivity) glass is coated with a microscopic layer of metallic oxides that reflect heat, helping to keep interiors cool in the summer and warm in the winter.
• Considerations: Low E glass comes in various types (e.g., standard, E2, E3), and each type has different properties. Applying window film to Low E glass requires careful consideration, as the film can potentially interfere with the glass’s reflective properties, leading to excessive heat absorption or reflection.

5. Clear Annealed Glass

• Definition: Clear annealed glass is standard glass that has been slowly cooled to relieve internal stresses. It’s the most common type of glass used in windows.
• Considerations: Clear annealed glass is compatible with most window films, but it is more prone to breakage compared to tempered glass. Understanding the film's impact on thermal stress is important for this glass type.

6. Tempered Glass

• Definition: Tempered glass is a type of safety glass that has been heat-treated to increase its strength. If it breaks, it shatters into small, less harmful pieces.
• Considerations: Because tempered glass is stronger and more resistant to thermal stress, it is usually compatible with a wider range of films. However, it’s essential to verify the film’s compatibility to avoid any issues.

7. Tinted Glass (1st Surface and 2nd Surface)

• Definition: Tinted glass has a colorant added to reduce glare and heat transmission. The terms "1st surface" and "2nd surface" refer to the position of the tint—1st surface tinting is on the exterior side, while 2nd surface tinting is on the interior side of the glass.
• Considerations: The location of the tint and the type of film applied can influence the performance of both the film and the glass. It’s important to choose a film that complements the tint without causing excessive heat absorption.

8. Laminated Glass

• Definition: Laminated glass consists of two or more layers of glass bonded together with a plastic interlayer. This construction enhances safety and security, as the glass holds together even when broken.
• Considerations: Laminated glass is commonly used in areas requiring additional safety, like skylights or hurricane-prone regions. The application of window film to laminated glass can further enhance safety, but care must be taken to ensure compatibility to prevent delamination or thermal stress.

9. Low E Standard, E2, and E3 Glass

• Definition: These are variations of Low E glass with different levels of emissivity. E2 and E3 refer to more advanced coatings that offer greater energy efficiency.
• Considerations: As with standard Low E glass, applying window film to E2 or E3 glass requires careful selection to avoid negatively impacting the glass’s reflective properties. Each level of Low E coating has specific compatibility requirements that must be considered.

Locating The Glass Type

Locating the glass type and determining specific details like which surfaces are tinted can be a bit tricky, especially if the window specs aren’t readily available. Here’s a guide on how someone can identify their glass type and gather relevant information:

1. Check for Manufacturer Labels or Stamps

• Look for Labels: Many windows, especially newer ones, will have a label or sticker in one of the corners of the glass. This label often includes information about the manufacturer, the type of glass, and any special coatings like Low E or tinting.
• Etched Stamps: Older windows might have an etched stamp on the glass itself, often in a corner, that indicates the manufacturer and glass type. This can include details like “Tempered” or “Laminated.”

2. Examine the Glass Edge

• Layered Appearance: For laminated glass, the edges may show a slight layering effect where the different layers of glass and the interlayer are visible.
• Thickness: The thickness of the glass can sometimes give clues about its type. For example, triple pane glass will be thicker than single or dual pane glass.

3. Inspect for Tinting

• Visual Inspection: To determine if the glass is tinted, perform a visual inspection. Tinted glass often has a slight color hue when viewed from the side or when compared to untinted glass. You can check both the exterior and interior sides of the window.
• Check Surface Position: Hold a piece of white paper against the glass on both the inside and outside. This can help reveal any tinting or reflective coatings. Tints on the 1st surface (exterior side) will be visible from the outside, while 2nd surface (interior side) tints will affect the view from inside.

4. Identify Low E Coatings

• Reflection Test: A simple way to check for Low E coatings is to hold a lighter or a match near the glass and observe the reflection. If you see multiple reflections with one having a slightly different color (often a faint blue or pink tint), it’s likely Low E coated.
• Feel the Glass: On a sunny day, touch the inside surface of the glass. If it feels cooler than you’d expect, it might have a Low E coating, which reflects heat back into the room.

5. Use a Polarized Lens Test

• Polarized Sunglasses: Put on a pair of polarized sunglasses and look at the window. If you notice a rainbow-like pattern or other anomalies, this could indicate that the glass has a Low E coating or is laminated.

6. Consult the Original Building Plans or Window Manufacturer

• Building Plans: If available, the original building plans or specifications should include details about the type of windows installed. This can be especially helpful in identifying glass types in larger buildings or commercial properties.
• Contact the Manufacturer: If you know the manufacturer, you can contact them directly with the model number (if available) or any other identifying information. They should be able to provide details on the glass type, coatings, and any other relevant specifications.

7. Professional Inspection

• Hire a Professional: If you’re unsure about the type of glass or coatings, hiring a professional to inspect the windows is a reliable option. Window specialists or glass companies can provide a detailed analysis and help identify the best type of film for your windows.

8. Using Online Resources or Tools

• Manufacturer Websites: Some manufacturers offer online tools where you can enter details like model numbers to get more information about your windows.
• Mobile Apps: There are mobile apps designed for energy audits and window assessments that can help you identify glass types and recommend solutions.

Bringing It All Together

Understanding your window’s specifications is the key to selecting the right window film. Once you’ve identified the glass type, whether it’s single pane, dual pane, low E, or tinted, you can cross-reference this information with the Flexfilm Film-to-Glass Compatibility Chart to find the most suitable window film. If you’re ever in doubt or need further assistance, Flexfilm is here to help.